Gas, dust and collisions in outer space One of the prograde moons has an angle of 36 degrees, similar to the other prograde moons close to Saturn named for Gallic mythology.
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It's orbiting in a prograde motion in the retrograde region.
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It moves among the retrograde moons yet orbits in a prograde direction.
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The newly discovered "oddball" moon has a prograde orbit, but it orbits farther from Jupiter than the other moons in the larger prograde group and it takes about one and a half Earth years to complete an orbit.
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Other prograde and distant retrograde moons complete a single orbit every three years.
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Most satellites, and even the rings of Saturn, also move in a prograde motion.
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It has a prograde orbit but is more distant and at a different incline.
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Most of these prograde moons take less than a year to travel around the planet.
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These moons are "prograde moons," meaning they orbit Jupiter in the same direction the planet spins.
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These are part of a group of prograde moons that orbit closer to Jupiter than the retrograde moons do.
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It orbits in the same general path as all of the retrograde moons, but in the opposite, prograde direction.
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The orbit is prograde and not sun-synchronous, which will help it avoid picking up a bias from tides.
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The "oddball" moon, known as Valetudo, can be seen in green in a prograde orbit that crosses over the retrograde orbits.
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These two groups of prograde and retrograde moons consist of "irregular" satellites , or moons whose orbits have irregular, or noncircular, shapes.
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This survivor could be the last remnant of a once-larger prograde moon that collided with an object to create the retrograde moons.
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Bigger moons like Europa and Ganymede typically orbit in the same direction as the rotation of their planet, in what astronomers call a prograde motion.
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Two of the new moons have prograde orbits, matching an inner group of moons that are thought to be fragments of a larger moon that shattered.
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Two of the newly discovered moons orbit much closer to Jupiter and have a prograde orbit, meaning that they orbit in the same direction as the planet.
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Because their orbits put them near other prograde moons, they're thought to be bits of a larger moon that was broken apart by a collision long ago.
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Two of the remaining moons are closer to Jupiter, with orbital periods of around one year, and they have normal prograde orbits that match the planet's rotation.
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What makes this celestial anomaly stranger still is that Jupiter is accompanied by 6,000 "Trojan" asteroids, the vast majority of which follow the gas giant in a prograde orbit.
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The final moon is the "oddball," according to the team, with a one-and-a-half year prograde orbit that transits through the outer retrograde group, which makes it prone to collisions.
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In our solar system, all of the planets and most of the other objects orbit in a prograde motion, meaning they're travelling in the same direction as the rotation of the sun.
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Direct motion or prograde motion is motion in the same direction as other bodies. While the terms direct and prograde are equivalent in this context, the former is the traditional term in astronomy. The earliest recorded use of prograde was in the early 18th century, although the term is now less common.
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Most natural satellites have prograde orbits about their planets. Prograde satellites of Uranus orbit in the direction Uranus rotates, which is retrograde to the Sun. Nearly all regular satellites are tidally locked and thus have prograde rotation. Retrograde satellites are generally small and distant from their planets, except Neptune's satellite Triton, which is large and close.
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Metamorphism is further divided into prograde and retrograde metamorphism. Prograde metamorphism involves the change of mineral assemblages (paragenesis) with increasing temperature and (usually) pressure conditions. These are solid state dehydration reactions, and involve the loss of volatiles such as water or carbon dioxide. Prograde metamorphism results in rock characteristic of the maximum pressure and temperature experienced.
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S/2004 S 24 has the most distant prograde orbit of Saturn's known satellites.
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All retrograde satellites are thought to have formed separately before being captured by their planets. Most low-inclination artificial satellites of Earth have been placed in a prograde orbit, because in this situation less propellant is required to reach orbit when launching in a prograde direction.
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Yarkovsky effect: 1\. Radiation from asteroid's surface 2\. Prograde rotating asteroid 2.1 Location with "Afternoon" 3\. Asteroid's orbit 4\.
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Metamorphism produced with increasing pressure and temperature conditions is known as prograde metamorphism. Conversely, decreasing temperatures and pressure characterize retrograde metamorphism.
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An Earth satellite that is in (a prograde) subsynchronous orbit will appear to drift eastward as seen from the Earth's surface.
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The direction of rotation is determined by an inertial frame of reference, such as distant fixed stars. In the Solar System, the orbits about the Sun of all planets and most other objects, except many comets, are prograde, i.e. in the same direction as the Sun rotates. Except for Venus and Uranus, planetary rotations are also prograde.
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'Themisto , also known as ', is a small prograde irregular satellite of Jupiter. It was discovered in 1975, subsequently lost, and rediscovered in 2000.
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A small radial impulse given to a body in orbit changes the eccentricity, but not the orbital period (to first order). A prograde or retrograde impulse (i.e. an impulse applied along the orbital motion) changes both the eccentricity and the orbital period. Notably, a prograde impulse at periapsis raises the altitude at apoapsis, and vice versa, and a retrograde impulse does the opposite.
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Sao is a prograde irregular satellite of Neptune. It was discovered by Matthew J. Holman et al. on August 14, 2002. Irregular satellites of Neptune.
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1937 The EZ is an exception to this rule, showing a strong eastward (prograde) jet and has a local minimum of the wind speed exactly at the equator. The jet speeds are high on Jupiter, reaching more than 100 m/s. These speeds correspond to ammonia clouds located in the pressure range 0.7–1 bar. The prograde jets are generally more powerful than the retrograde jets.
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This was thought to explain the preponderance of retrograde moons around Jupiter; however, Saturn has a more even mix of retrograde/prograde moons so the reasons are more complicated.
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The Sun's motion about the centre of mass of the Solar System is complicated by perturbations from the planets. Every few hundred years this motion switches between prograde and retrograde.
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ProGrade Digital announced it would begin production and sale of CFexpress cards in 2018 with the Type-B form-factor (the same as XQD). The 1 TB CFexpress card that ProGrade Digital showed at the Spring NAB show in 2018 demonstrated 1,400 Mbit/s (Mbyte/sec?)read speed and over 700 Mbit/s (Mbyte/sec?)burst write speed. This demonstration was performed using a Thunderbolt 3 CFexpress/XQD reader on aprograde digital incorporated MacBook Pro computer.
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A celestial object's axial tilt indicates whether the object's rotation is prograde or retrograde. Axial tilt is the angle between an object's rotation axis and a line perpendicular to its orbital plane passing through the object's centre. An object with an axial tilt up to 90 degrees is rotating in the same direction as its primary. An object with an axial tilt of exactly 90 degrees has a perpendicular rotation that is neither prograde nor retrograde.
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All the other retrograde satellites are on distant orbits and tidal forces between them and the planet are negligible. Within the Hill sphere, the region of stability for retrograde orbits at a large distance from the primary is larger than that for prograde orbits. This has been suggested as an explanation for the preponderance of retrograde moons around Jupiter. Because Saturn has a more even mix of retrograde/prograde moons, however, the underlying causes appear to be more complex.
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Manganese is suggestive of prograde metamorphism. Overall it has been suggested that there were three metamorphic events, occurring 3.74 billion years ago, 3.69 billion years ago, and at 2.8 billion years ago.
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Most of the winds on Neptune move in a direction opposite the planet's rotation.Burgess (1991):64–70. The general pattern of winds showed prograde rotation at high latitudes vs. retrograde rotation at lower latitudes.
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Also visible is the mutual tidal locking between the two bodies. The Pluto system is highly compact and largely empty: Prograde moons could stably orbit Pluto out to 53% of the Hill radius (the gravitational zone of Pluto's influence) of 6 million km, or out to 69% for retrograde moons. However, only the inner 3% of the region where prograde orbits would be stable is occupied by satellites, and the region from Styx to Hydra is packed so tightly that there is little room for further moons with stable orbits within this region. An intense search conducted by New Horizons confirmed that no moons larger than 4.5 km in diameter exist out to a distances up to 180,000 km from Pluto (6% of the stable region for prograde moons), assuming Charon-like albedoes of 0.38 (for smaller distances, this threshold is still smaller).
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The Poynting-Robertson effect is a force opposing the object's velocity caused by asymmetric incidence of light, i.e., aberration of light. For an object with prograde rotation, these two effects will apply opposing, but generally unequal, forces.
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All three minerals preferentially fractionate Y, yet they form and break down at different stages of metamorphism. Xenotime has the highest fractionating power, then garnet and then monazite. In a simplified case of a clockwise P-T path involving garnet and monazite, garnet grows along a prograde path with Y continuously being incorporated, thus the Y content in monazite formed at this stage (prograde) should decrease progressively with higher grade. However, as temperature increases to a certain point, partial melting (anatectic) of monazite occurs around its rim, releasing Y into the melts.
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A triple conjunction is an astronomical event where two planets or a planet and a star meet each other three times in a short period, either in opposition or at the time of inferior conjunction, if an inferior planet is involved. The visible movement of the planet or the planets in the sky is therefore normally prograde at the first conjunction, retrograde at the second conjunction and again prograde at the third conjunction. The lining-up of three planets is a particular case of syzygy. There are three possible cases of triple conjunctions.
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EPSC/DPS conference 2011, Nantes (France), abstract 1452. Irregular prograde groups of satellites of Saturn: Gallic (red) and Inuit (blue) The diagram illustrates the Albiorigian orbit in relation to other prograde irregular satellites of Saturn. The eccentricity of the orbits is represented by the yellow segments extending from the pericentre to the apocentre. Given the similarity of the orbital elements and the homogeneity of the physical characteristics with other members of the Gallic group, it was suggested that these satellites could have a common origin in the break-up of a larger moon.
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By coincidence, if the thumb is pointing north, Earth rotates in a prograde direction according to the right-hand rule. This causes the Sun, Moon, and stars to appear to revolve westward according to the left-hand rule.
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Anticlockwise evolution of ultrahigh- temperature granulites within continental collision zone in southern India. Lithos 92, 447–464.Shimpo, M., Tsunogae, T., Santosh, M., 2006. First report of garnet–corundum rocks from southern India: implications for prograde high- pressure (eclogite-facies?)metamorphism.
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Retrograde orbit: the satellite (red) orbits in the direction opposite to the rotation of its primary (blue/black) Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure). It may also describe other motions such as precession or nutation of an object's rotational axis. Prograde or direct motion is more normal motion in the same direction as the primary rotates. However, "retrograde" and "prograde" can also refer to an object other than the primary if so described.
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Of Jupiter's moons, eight are regular satellites with prograde and nearly circular orbits that are not greatly inclined with respect to Jupiter's equatorial plane. The Galilean satellites are nearly spherical in shape due to their planetary mass, and so would be considered at least dwarf planets if they were in direct orbit around the Sun. The other four regular satellites are much smaller and closer to Jupiter; these serve as sources of the dust that makes up Jupiter's rings. The remainder of Jupiter's moons are irregular satellites whose prograde and retrograde orbits are much farther from Jupiter and have high inclinations and eccentricities.
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Kohn, M. J., & Malloy, M. A. (2004). Formation of monazite via prograde metamorphic reactions among common silicates: implications for age determinations. Geochimica et Cosmochimica Acta, 68(1), 101–113. This is one of the principal reasons for the compositional variation of monazite.
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His wife's name is Tania Clarke. His children's names are Christian Xavier Clarke, Mckenzie Clarke, Adrien Clarke II, Aaron Clarke, Driana Smith, Aiden Clarke, and Parker Clarke. Now he is the owner and CEO of Prograde Performance where he trains young athletes.
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They both exhibit high closure temperatures which makes them suitable for recording igneous and metamorphic events. However, they behave differently throughout their geological history.Rubatto, D., Williams, I. S., & Buick, I. S. (2001). Zircon and monazite response to prograde metamorphism in the Reynolds Range, central Australia.
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S/2004 S 24 is a natural satellite of Saturn, and the outermost known prograde satellite. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on October 7, 2019 from observations taken between December 12, 2004 and March 22, 2007. S/2004 S 24 is about 3 kilometres in diameter, and orbits Saturn at an average distance of 22,901 Gm in 1294.25 days, at an inclination of 35.5° to the ecliptic, in a prograde direction and with an eccentricity of 0.085. Due to its inclination being similar to the four known members of the Gallic group, S/2004 S 24 could belong to the Gallic group.
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Laomedeia , also known as Neptune XII, is a prograde irregular satellite of Neptune. It was discovered by Matthew J. Holman, et al. on August 13, 2002. Before the announcement of its name on February 3, 2007 (IAUC 8802), it was known as S/2002 N 3.
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Manganese rich species can be found in metamorphosed Mn-rich rock units. The grunerite end member is characteristic of the metamorphosed iron formations of the Lake Superior region and the Labrador Trough. With prograde metamorphism cummingtonite and grunerite morph to members of the olivine and pyroxene series.
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Vesta's rotation is relatively fast for an asteroid (5.342 h) and prograde, with the north pole pointing in the direction of right ascension 20 h 32 min, declination +48° (in the constellation Cygnus) with an uncertainty of about 10°. This gives an axial tilt of 29°.
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Like the sun, the planets appear to rise in the East and set in the West. When a planet travels eastward in relation to the stars, it is called prograde. When the planet travels westward in relation to the stars (opposite path) it is called retrograde.
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All inner satellites follow nearly circular, prograde orbits. The median eccentricity is 0.0012, while the most eccentric inner satellite is Thebe with e=0.0177. Their inclination to their planets' equatorial planes is also very low. All but one have inclinations below one degree, the median being 0.1°.
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Margaret is the only prograde irregular satellite of Uranus. It was discovered by Scott S. Sheppard, et al. in 2003 and given the provisional designation S/2003 U 3. Confirmed as Uranus XXIII, it was named after the servant of Hero in William Shakespeare's play Much Ado About Nothing.
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Based on a prograde orbit model, Xiangliu orbits Gonggong at a distance of around and completes one orbit in 25.22 days. Using the same prograde orbit model, the discovery team has estimated that its orbit is inclined to the ecliptic by about 83 degrees, implying that Gonggong is being viewed at a nearly pole-on configuration under the assumption that Xiangliu's orbit has a low inclination to Gonggong's equator. The orbit of Xiangliu is highly eccentric. The value of 0.29 is thought to have been caused by either an intrinsically eccentric orbit or by slow tidal evolution, in which the time for its orbit to circularize is comparable to the age of the Solar System.
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Hollis, J. A., Harley, S. L., White, R. W., and Clarke, G. L., 2006, Preservation of evidence for prograde metamorphism in UHT HP granulites, South Harris, Scotland: Journal of Metamorphic Geology, v. 24, p. 263–279. UHT rocks from the Neoproterozoic Grenville orogeny are distributed in the Eastern Ghats Province, India.
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Since the inclination is less than 90°, Dysnomia's orbit is therefore prograde relative to Eris's orbit. In 2239, Eris and Dysnomia will enter a period of mutual events in which Dysnomia's orbital plane is aligned edge-on to the Sun, allowing for Eris and Dysnomia to take turns eclipsing each other.
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Most Kuiper belt objects have prograde orbits around the Sun. The first Kuiper belt object discovered to have a retrograde orbit was . Other Kuiper belt objects with retrograde orbits are (471325) 2011 KT19, , and 2011 MM4. All of these orbits are highly tilted, with inclinations in the 100°–125° range.
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The word "geosynchronous" is sometimes used to describe quasi-satellites of the Earth, because their motion around the Sun is synchronized with Earth's. However, this usage is unconventional and confusing. Conventionally, geosynchronous satellites revolve in the prograde sense around the Earth, with orbital periods that are synchronized to the Earth's rotation.
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The moon is located midway between the Galilean moons and the first group of prograde irregular moons, called the Himalia group. Themisto is about 8 kilometers (5 miles) in diameter (assuming an albedo of 0.04). That figure can be used to find a surface area of between 200 and 380 square kilometers.
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3 Although planets can sometimes be mistaken for stars as one observes the night sky, the planets actually change position from night to night in relation to the stars. Retrograde (backward) and prograde (forward) are observed as though the stars revolve around the Earth. Ancient Greek astronomer Ptolemy in 150 AD believed that the Earth was the center of the Solar System and therefore used the terms retrograde and prograde to describe the movement of the planets in relation to the stars. Although it is known today that the planets revolve around the sun, the same terms continue to be used in order to describe the movement of the planets in relation to the stars as they are observed from Earth.
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Halimede has the second most eccentric and third most inclined orbit around Neptune. This is illustrated on the diagram in relation to other irregular satellites of Neptune. The satellites above the horizontal axis are prograde, the satellites beneath it are retrograde. The yellow segments extend from the pericentre to the apocentre, showing the eccentricity.
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Ida has a moon named Dactyl, official designation (243) Ida I Dactyl. It was discovered in images taken by the Galileo spacecraft during its flyby in 1993. These images provided the first direct confirmation of an asteroid moon. At the time, it was separated from Ida by a distance of , moving in a prograde orbit.
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85, 91–4. The North Temperate Region is part of a latitudinal region easily observable from Earth, and thus has a superb record of observation.Rogers (1995), pp. 101–105. It also features the strongest prograde jet stream on the planet—a westerly current that forms the southern boundary of the North Temperate Belt (NTB).
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An object with an inclination between 0 and 90 degrees is orbiting or revolving in the same direction as the primary is rotating. An object with an inclination of exactly 90 degrees has a perpendicular orbit that is neither prograde nor retrograde. An object with an inclination between 90 degrees and 180 degrees is in a retrograde orbit.
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All known dwarf planets and dwarf planet candidates have prograde orbits around the Sun, but some have retrograde rotation. Pluto has retrograde rotation; its axial tilt is approximately 120 degrees. Pluto and its moon Charon are both tidally locked to each other. It is suspected that the Plutonian satellite system was created by a massive collision.
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The spot is spatially confined by a modest eastward jet stream (prograde) to its south and a very strong westward (retrograde) one to its north.Beebe (1997), p. 35. Though winds around the edge of the spot peak at about 120 m/s (432 km/h), currents inside it seem stagnant, with little inflow or outflow.Rogers (1995), p. 195.
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The diagram illustrates the orbits of Neptune's irregular moons excluding Triton. The eccentricity is represented by the yellow segments extending from the pericenter to apocenter with the inclination represented on Y axis. The moons above the X axis are prograde, those beneath are retrograde. The X axis is labeled in Gm and the fraction of the Hill sphere's radius.
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The lifetime of moons in the instability region is from 10 million to a billion years. Margaret is the only known irregular prograde moon of Uranus, and it currently has the most eccentric orbit of any moon in the Solar System, though Neptune's moon Nereid has a higher mean eccentricity. As of 2008, Margaret's eccentricity is 0.7979.
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Siarnaq, also designated Saturn XXIX, is a prograde irregular satellite of Saturn. It was discovered at the Mauna Kea Observatory by astronomers Brett Gladman and John Kavelaars in 2000, and given the temporary designation S/2000 S 3. Named after Siarnaq, the Inuit goddess of the sea, it is the largest member of the Inuit group of irregular satellites.
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Tarvos , or Saturn XXI, is a prograde irregular satellite of Saturn. It was discovered by John J. Kavelaars et al. on September 23, 2000, and given the temporary designation S/2000 S 4\. The name, given in August 2003, is after Tarvos, a deity depicted as a bull god carrying three cranes alongside its back from Gaulish mythology.
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Proteus is the second-largest moon of Neptune and is the largest of the regular prograde moons of Neptune. It is about in diameter, larger than Nereid, Neptune's third-largest moon. It was not discovered by Earth-based telescopes because Proteus orbits so close to Neptune that it is lost in the glare of reflected sunlight.
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During the giant impact stage, the thickness of a protoplanetary disk is far larger than the size of planetary embryos so collisions are equally likely to come from any direction in three- dimensions. This results in the axial tilt of accreted planets ranging from 0 to 180 degrees with any direction as likely as any other with both prograde and retrograde spins equally probable. Therefore, prograde spin with a small axial tilt, common for the Solar System's terrestrial planets except Venus, is not common in general for terrestrial planets built by giant impacts. The initial axial tilt of a planet determined by giant impacts can be substantially changed by stellar tides if the planet is close to its star and by satellite tides if the planet has a large satellite.
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Elara is a prograde irregular satellite of Jupiter. It was discovered by Charles Dillon Perrine at Lick Observatory in 1905. It is the eighth-largest moon of Jupiter and is named after Elara, one of Zeus's lovers and the mother of the giant Tityos. Elara did not receive its present name until 1975; before then, it was simply known as '.
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Lysithea is a prograde irregular satellite of Jupiter. It was discovered by Seth Barnes Nicholson in 1938 at Mount Wilson Observatory and is named after the mythological Lysithea, daughter of Oceanus and one of Zeus' lovers. Lysithea did not receive its present name until 1975; before then, it was simply known as '. It was sometimes called "Demeter" from 1955 to 1975.
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At the equator winds are retrograde, which means that they blow in the reverse direction to the planetary rotation. Their speeds are from . Wind speeds increase with the distance from the equator, reaching zero values near ±20° latitude, where the troposphere's temperature minimum is located. Closer to the poles, the winds shift to a prograde direction, flowing with Uranus's rotation.
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The structure of the halo is the topic of an ongoing debate. Several studies have claimed to find a halo consisting of two distinct components. These studies find a "dual" halo, with an inner, more metal-rich, prograde component (i.e. stars orbit the galaxy on average with the disk rotation), and a metal-poor, outer, retrograde (rotating against the disc) component.
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This fact may be a sign of tidal heating due to interactions with another planet. At Jupiter-like distances its radius would roughly be the same as Jupiter. The complete phase curve of this planet has been observed. CoRoT-2b orbits its star approximately once every 1.7 days, and orbits the star in a prograde direction close to the star's equator.
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Diagram illustrating Themisto's orbit (top left) among those of the other irregular satellites of Jupiter. The satellites above the horizontal axis are prograde, the satellites beneath it are retrograde. The yellow segments extend from the pericentre to the apocentre, showing the orbital eccentricity. Themisto's orbit is unusual: unlike most of Jupiter's moons, which orbit in distinct groups, Themisto orbits alone.
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Lightcurve-based 3D-model of Hebe Size comparison: the first 10 asteroids profiled against the Moon. Hebe is sixth from the left. Lightcurve analysis suggests that Hebe has a rather angular shape, which may be due to several large impact craters. Hebe rotates in a prograde direction, with the north pole pointing towards ecliptic coordinates (β, λ) = (45°, 339°) with a 10° uncertainty.
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Metamorphic rocks usually do not undergo further change when they are brought back to the surface. Retrograde metamorphism involves the reconstitution of a rock via revolatisation under decreasing temperatures (and usually pressures), allowing the mineral assemblages formed in prograde metamorphism to revert to those more stable at less extreme conditions. This is a relatively uncommon process, because volatiles must be present.
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An animation of Earth's rotation around the planet's axis long-exposure photo of the northern night sky above the Nepali Himalayas shows the apparent paths of the stars as Earth rotates. DSCOVR EPIC on 29 May 2016, a few weeks before the solstice. Earth's rotation is the rotation of planet Earth around its own axis. Earth rotates eastward, in prograde motion.
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The orbits of the known irregular satellites are extremely diverse, but there are certain patterns. Retrograde orbits are far more common (83%) than prograde orbits. No satellites are known with orbital inclinations higher than 55° (or smaller than 130° for retrograde satellites). In addition, some groupings can be identified, in which one large satellite shares a similar orbit with a few smaller ones.
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This fact may be a sign of tidal heating due to interactions with another planet. At Jupiter-like distances its radius would roughly be the same as Jupiter. The complete phase curve of this planet has been observed. CoRoT-2b orbits its star approximately once every 1.7 days, and orbits the star in a prograde direction close to the star's equator.
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Valetudo has a diameter of about and orbits Jupiter at a distance of about . Its orbital inclination is 34 degrees, and its orbital eccentricity is 0.222. It has a prograde orbit which takes almost a year and a half to complete, but it crosses paths with several other moons that have retrograde orbits and may in the future collide with them.
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Retrieved on 2013-11-08. This equation is sometimes also referred to as the Vukančić–Vuković equation.Journal on Modeling Prograde TiO2 Activity and its significance for Ti in Quartz Thermobarometry of Pelitic Metamorphic Rocks. Academia.edu. p. 2.Journal on Indirect spectrophotometric determination of folic acid based on the oxidation reaction and studying some of the thermodynamic parameters. Academia.edu. p. 67.
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Most planets in our solar system, including Earth, spin in the same direction as they orbit the Sun. The exceptions are Venus and Uranus. Uranus rotates nearly on its side relative to its orbit. Current speculation is that Uranus started off with a typical prograde orientation and was knocked on its side by a large impact early in its history.
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16, p. 819–841.Baba, S., 1999, Sapphirine-bearing orthopyroxene-kyanite/sillimanite granulites from South Harris, NW Scotland: Evidence for Proterozoic UHT metamorphism in the Lewisian: Contributions to Mineralogy and Petrology, v. 136, p. 33–47.Baba, S., 2003, Two stages of sapphirine formation during prograde and retrograde metamorphism in the Paleoproterozoic Lewisian complex in South Harris, NW Scotland: Journal of Petrology, v. 44, p. 329–354.
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This is due to the loss of fluids (e.g. CO2, H2O) from prograde metamorphism, after which there is insufficient fluid to permit reverse reaction of the mineral assemblages. Another reason is that the rocks are of inappropriate composition to generate all the minerals that record their complete metamorphic events. On average, only one-in-twenty metamorphic rock samples display all the three stages of metamorphism.
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The combined orbits of the three stars together give a parallax significantly more precise than the HIPPARCOS parallax. The inclinations of the two orbits are known accurately enough to calculate their relative inclination. The two orbital planes are within 30° of being orthogonal, with the inner orbit being prograde and the outer retrograde. Although slightly surprising, this situation is not necessarily rare in triple systems.
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Artificial satellites destined for low inclination orbits are usually launched in the prograde direction, since this minimizes the amount of propellant required to reach orbit by taking advantage of the Earth's rotation (an equatorial launch site is optimal for this effect). However, Israeli Ofeq satellites are launched in a westward, retrograde direction over the Mediterranean to ensure that launch debris does not fall onto populated land areas.
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The eastward (prograde) jets are found at the transition from zones to belts (going away from the equator), whereas westward (retrograde) jets mark the transition from belts to zones. Such flow velocity patterns mean that the zonal winds decrease in belts and increase in zones from the equator to the pole. Therefore, wind shear in belts is cyclonic, while in zones it is anticyclonic.Vasavada (2005), p.
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Current IAU practice for newly discovered Neptunian moons is to accord with these first two choices by naming them after Greek sea deities. For the "normal" irregular satellites, the general convention is to use names ending in "a" for prograde satellites, names ending in "e" for retrograde satellites, and names ending in "o" for exceptionally inclined satellites, exactly like the convention for the moons of Jupiter.
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For a typical prograde orbit around Earth (that is, in the direction of primary body's rotation), the longitude of the ascending node decreases, that is the node precesses westward. If the orbit is retrograde, this increases the longitude of the ascending node, that is the node precesses eastward. This nodal progression enables heliosynchronous orbits to maintain a nearly constant angle relative to the Sun.
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Prograde orbits dominate tight binary systems such as 469705 ǂKá̦gára, those with satellite semimajor axes less than about 5% of their Hill radii. Grundy et al. suggest that this could be "the signature of planetesimal formation through gravitational collapse of local density enhancements such as caused by the streaming instability", which has been suggested as the formative mechanism of the only visited planetesimal, 486958 Arrokoth.
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Closer to the poles, the winds shift to a prograde direction, flowing with its rotation. Wind speeds continue to increase reaching maxima at ±60° latitude before falling to zero at the poles. Wind speeds at −40° latitude range from 150 to 200 m/s. Because the collar obscures all clouds below that parallel, speeds between it and the south pole are impossible to measure.
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Foliation is common in rocks affected by the regional metamorphic compression typical of areas of mountain belt formation (orogenic belts). More technically, foliation is any penetrative planar fabric present in metamorphic rocks. Rocks exhibiting foliation include the standard sequence formed by the prograde metamorphism of mudrocks; slate, phyllite, schist and gneiss. The slatey cleavage typical of slate is due to the preferred orientation of microscopic phyllosilicate crystals.
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Of the eight solar planets, all but Venus and Uranus have prograde rotation—that is, they rotate more than once per year in the same direction as they orbit the Sun, so the Sun rises in the east. Venus and Uranus, however, have retrograde rotation. For prograde rotation, the formula relating the lengths of the sidereal and solar days is: or, equivalently: On the other hand, the formula in the case of retrograde rotation is: or, equivalently: All the solar planets more distant from the Sun than Earth are similar to Earth in that, since they experience many rotations per revolution around the Sun, there is only a small difference between the length of the sidereal day and that of the solar day – the ratio of the former to the latter never being less than Earth's ratio of 0.997. But the situation is quite different for Mercury and Venus.
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Dia , also known as Jupiter LIII, is a prograde irregular satellite of Jupiter. Provisionally known as S/2000 J 11, it received its name on March 7, 2015.CBET (Central Bureau Electronic Telegram) 4075: 20150307: Satellites of Jupiter, March 7, 2015 It is named after Dia, daughter of Deioneus (or Eioneus), wife of Ixion. According to Homer, she was seduced by Zeus in stallion form; Pirithous was the issue.
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Sao orbits Neptune at a distance of about 22.4 million km and is about 44 kilometers in diameter (assuming an albedo of 0.04). Sao follows an exceptionally inclined and moderately eccentric orbit illustrated on the diagram in relation to other irregular satellites of Neptune. The satellites above the horizontal axis are prograde, the satellites beneath it are retrograde. The yellow segments extend from the pericentre to the apocentre, showing the eccentricity.
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As of 2005 Uranus is known to have nine irregular moons, which orbit it at a distance much greater than that of Oberon, the furthest of the large moons. All the irregular moons are probably captured objects that were trapped by Uranus soon after its formation. The diagram illustrates the orbits of those irregular moons discovered so far. The moons above the X axis are prograde, those beneath are retrograde.
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Foliation may be formed by realignment of micas and clays via physical rotation of the minerals within the rock. Often this foliation is associated with diagenetic metamorphism and low-grade burial metamorphism. Foliation may parallel original sedimentary bedding, but more often is oriented at some angle to it. The growth of platy minerals, typically of the mica group, is usually a result of prograde metamorphic reactions during deformation.
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This chosen period roughly corresponds to the prograde rotation at a latitude of 26° north or south, which is consistent with the typical latitude of sunspots and corresponding periodic solar activity. When the Sun is viewed from the "north" (above Earth's north pole), solar rotation is counterclockwise (eastward). To a person standing on the North Pole, sunspots would appear to move from left to right across the Sun's face.
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The "hot Jupiter" class planet WASP-32 b, later named 'Viculus', was discovered around WASP-32 in 2010. It was found to orbit the parent star in prograde direction in 2014. The follow-up study utilizing transit timing variation analysis, have failed to find any, therefore have excluded existence of other massive planets around WASP-32 as in 2015.Lei-Lei Sun, Sheng-Hong Gu, Xiao-Bin Wang at al.
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Hence any light that reaches an outside observer from the photon sphere must have been emitted by objects between the photon sphere and the event horizon. For a Kerr black hole the radius of the photon sphere depends on the spin parameter and on the details of the photon orbit, which can be prograde (the photon rotates in the same sense of the black hole spin) or retrograde.
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It is generally thought that natural satellites should orbit in the same direction as the planet is rotating (known as prograde orbit). As such, the terminology regular moon is used for these orbit. However a retrograde orbit (the opposite direction to the planet) is also possible, the terminology irregular moon is used to describe known exceptions to the rule, it is believed that irregular moons have been inserted into orbit through gravitational capture.
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In the case of the Sun, even this criterion fails (because its magnetosphere is very complex and does not really rotate in a steady fashion), and an agreed-upon value for the rotation of its equator is used instead. For planetographic longitude, west longitudes (i.e., longitudes measured positively to the west) are used when the rotation is prograde, and east longitudes (i.e., longitudes measured positively to the east) when the rotation is retrograde.
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Two possible orbits for Weywot have been determined from the observations: the first is a prograde orbit with an orbital inclination of 14 degrees, the second a retrograde orbit with an orbital inclination of 30 degrees (150 degrees); the other parameters are very similar between the two orbits. Weywot orbits at a distance of from Quaoar and has an orbital eccentricity of about 0.14, it completes one orbit in about 12.5 days.
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Pallas's rotation appears to be prograde. Pallas is thought to have undergone at least some degree of thermal alteration and partial differentiation, which suggests that it is a remnant protoplanet. During the planetary formation stage of the Solar System, objects grew in size through an accretion process to approximately this size. Many of these objects were incorporated into larger bodies, which became the planets, whereas others were destroyed in collisions with other protoplanets.
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Diagram of potential orbits of Dactyl around Ida Dactyl's orbit around Ida is not precisely known. Galileo was in the plane of Dactyl's orbit when most of the images were taken, which made determining its exact orbit difficult. Dactyl orbits in the prograde direction and is inclined about 8° to Ida's equator. Based on computer simulations, Dactyl's pericenter must be more than about from Ida for it to remain in a stable orbit.
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It was his first of two asteroid discoveries. The second was 6 Hebe. A German amateur astronomer and post office headmaster, Hencke was looking for 4 Vesta when he stumbled on Astraea. The King of Prussia awarded him an annual pension of 1,200 marks for the discovery. Photometry indicates prograde rotation, that the north pole points in the direction of right ascension 9 h 52 min, declination 73° with a 5° uncertainty.
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The moons of Neptune can be divided into two groups: regular and irregular. The first group includes the seven inner moons, which follow circular prograde orbits lying in the equatorial plane of Neptune. The second group consists of all seven other moons including Triton. They generally follow inclined eccentric and often retrograde orbits far from Neptune; the only exception is Triton, which orbits close to the planet following a circular orbit, though retrograde and inclined.
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Twenty- four of Saturn's moons are regular satellites; they have prograde orbits not greatly inclined to Saturn's equatorial plane. They include the seven major satellites, four small moons that exist in a trojan orbit with larger moons, two mutually co-orbital moons and two moons that act as shepherds of Saturn's F Ring. Two other known regular satellites orbit within gaps in Saturn's rings. The relatively large Hyperion is locked in a resonance with Titan.
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The Inuit group includes seven prograde outer moons that are similar enough in their distances from the planet (186–297 radii of Saturn), their orbital inclinations (45–50°) and their colors that they can be considered a group. The moons are Ijiraq, Kiviuq, Paaliaq, Siarnaq, and Tarqeq, along with two unnamed moons S/2004 S 29 and S/2004 S 31. The largest among them is Siarnaq with an estimated size of about 40 km.
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Lawsonite is a metamorphic silicate mineral related chemically and structurally to the epidote group of minerals. It is close to the ideal composition of CaAl2Si2O7(OH)2 . H2O giving it a close chemical composition with anorthite CaAl2Si2O8 (its anhydrous equivalent), yet lawsonite has greater density and a different Al coordination (Comodi et al., 1996). The substantial amount of water bound in lawsonite’s crystal structure is released during its breakdown to denser minerals during prograde metamorphism.
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The secondary star is likely a red dwarf from its low mass. In 2009, the system was hypothesized to contain an exoplanet based on perturbations in the orbital period. A prograde solution was quickly ruled out but a retrograde solution remains a possibility, although the variations may instead be due to the secondary star being itself a close binary, since the formation of a planet in such a system would difficult due to dynamic perturbations.
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Basic depositional model of the Northern Shelf of the Permian Basin showing the three main depositional environments associated with Slaughter Field. The region of Slaughter Field can be characterized by three main depositional environments: the shoals of the shelf margin, lagoonal evaporites, and the wackestones and packstones in the tidal flats. These environments result from the cyclic deposits in a regressive series. These deposits prograde to the south across the broad, shallow marine Northern Shelf.
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As tectonic uplift of central Borneo continued into the lower Miocene, the westernmost portion of the Kutai Basin was inverted above sea level, forming the Upper Kutai Basin. There was a significant change in the character of sedimentation in the Kutai Basin in the Early Miocene. Large amounts of clastic sediment derived from the rising central mountains, and the now inverted Paleogene poured into the lower Kutai Basin. The proto- Mahakam river began to prograde eastward.
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A celestial object's inclination indicates whether the object's orbit is prograde or retrograde. The inclination of a celestial object is the angle between its orbital plane and another reference frame such as the equatorial plane of the object's primary. In the Solar System, inclination of the planets is measured from the ecliptic plane, which is the plane of Earth's orbit around the Sun. The inclination of moons is measured from the equator of the planet they orbit.
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In the Solar System, many of the asteroid-sized moons have retrograde orbits, whereas all the large moons except Triton (the largest of Neptune's moons) have prograde orbits. The particles in Saturn's Phoebe ring are thought to have a retrograde orbit because they originate from the irregular moon Phoebe. All retrograde satellites experience tidal deceleration to some degree. The only satellite in the Solar System for which this effect is non-negligible is Neptune's moon Triton.
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Close-flybys and mergers of galaxies within galaxy clusters can pull material out of galaxies and create small satellite galaxies in either prograde or retrograde orbits around larger galaxies.M. S. Pawlowski, P. Kroupa, and K. S. de Boer, "Making Counter-Orbiting Tidal Debris – The Origin of the Milky Way Disc of Satellites" A galaxy called Complex H, which was orbiting the Milky Way in a retrograde direction relative to the Milky Way's rotation, is colliding with the Milky Way.
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The center of a spiral galaxy contains at least one supermassive black hole. A retrograde black hole – one whose spin is opposite to that of its disk – spews jets much more powerful than those of a prograde black hole, which may have no jet at all. Scientists have produced a theoretical framework for the formation and evolution of retrograde black holes based on the gap between the inner edge of an accretion disk and the black hole.
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The meridional extent of them appears to match the actual width of jets. Therefore, in shallow models vortices actually feed the jets and should disappear by merging into them. While these weather–layer models can successfully explain the existence of a dozen narrow jets, they have serious problems. A glaring failure of the model is the prograde (super-rotating) equatorial jet: with some rare exceptions shallow models produce a strong retrograde (subrotating) jet, contrary to observations.
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Based on Hubble images of Gonggong and Xiangliu taken in 2009 and 2010, the discovery team constrained Xiangliu's orbital period to between 20 and 100 days. They better determined the orbit with additional Hubble observations in 2017. Xiangliu is believed to be tidally locked to Gonggong. Because the observations of Xiangliu only span a small fraction of Gonggong's orbit around the Sun, it is not yet possible to determine whether Xiangliu's orbit is prograde or retrograde.
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In the northern Dinaride Mountains, flysch several meters thick grades from Maastrichtian sandstone, siltstone and shale into Paleocene calcite shale, calcareous sandstone, sandy limestones and limestones. The flysch is overlain by more limestone from the Middle Eocene. In some cases, the interlayering of Late Cretaceous-Paleogene flysch with volcanic rocks has resulted in medium-pressure metamorphism. Rock sequences prograde from sandstone, shale, marl and limestone to slate and meta-sandstone along with greenschist, mica schist, amphibolite, gneiss and phyllite.
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P-T-t paths often reflect various stages of the metamorphic cycle. A metamorphic cycle implies the series of processes that a rock experienced from burial, heating to uplift and erosion. The P-T conditions experienced by a rock throughout these processes can be classified into three main stages according to temperature changes: # Prograde (pre-peak) metamorphism: the process when the rock is buried and heated in environments such as basins or subduction zones. Devolatilization reactions (release of gases e.g.
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The metamorphic mineralogy of ultramafic rocks, particularly komatiites, is only partially controlled by composition. The character of the connate fluids which are present during low temperature metamorphism whether prograde or retrograde control the metamorphic assemblage of a metakomatiite (hereafter the prefix meta- is assumed). The factor controlling the mineral assemblage is the partial pressure of carbon dioxide within the metamorphic fluid, called the XCO2. If XCO2 is above 0.5, the metamorphic reactions favor formation of talc, magnesite (magnesium carbonate), and tremolite amphibole.
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Retrograde motion, or retrogression, within the Earth's atmosphere is seen in weather systems whose motion is opposite the general regional direction of airflow, i.e. from east to west against the westerlies or from west to east through the trade wind easterlies. Prograde motion with respect to planetary rotation is seen in the atmospheric super-rotation of the thermosphere of Earth and in the upper troposphere of Venus. Simulations indicate that the atmosphere of Pluto should be dominated by winds retrograde to its rotation.
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This occurs because, as the river widens at the mouth, the flow slows, and sediment settles out and is deposited. After initial formation of a river mouth bar, they have the tendency to prograde. This is caused by the pressure from the flow on the upstream face of the bar. This pressure creates erosion on that face of the bar, allowing the flow to transport this sediment over or around, and re-deposit it farther downstream, closer to the ocean.
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Among the remaining irregular moons, Sao and Laomedeia follow prograde orbits, whereas Halimede, Psamathe and Neso follow retrograde orbits. Given the similarity of their orbits, it was suggested that Neso and Psamathe could have a common origin in the break-up of a larger moon. Psamathe and Neso have the largest orbits of any natural satellites discovered in the Solar system to date. They take 25 years to orbit Neptune at an average of 125 times the distance between Earth and the Moon.
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Two more were discovered in 2016 by the team led by Scott S. Sheppard at the Carnegie Institution for Science, bringing the total to 69. On 17 July 2018, the International Astronomical Union confirmed that Sheppard's team had discovered ten more moons around Jupiter, bringing the total number to 79. Among these is Valetudo, which has a prograde orbit, but crosses paths with several moons that have retrograde orbits, making an eventual collision—at some point on a billions-of-years timescale—likely.
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Grav, Tommy; Holman, Matthew J.; Gladman, Brett J.; Aksnes, Kaare Photometric survey of the irregular satellites, Icarus, 166,(2003), pp. 33-45. Preprint The radius of the parent asteroid was probably about 89 km, only slightly larger than that of Himalia, which retains approximately 87% of the mass of the original body. This indicates the asteroid was not heavily disturbed. Numerical integrations show a high probability of collisions among the members of the prograde group during the lifespan of the solar system (e.g.
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The acceleration causes a gradual recession of a satellite in a prograde orbit away from the primary, and a corresponding slowdown of the primary's rotation. The process eventually leads to tidal locking, usually of the smaller first, and later the larger body. The Earth–Moon system is the best-studied case. The similar process of tidal deceleration occurs for satellites that have an orbital period that is shorter than the primary's rotational period, or that orbit in a retrograde direction.
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To-scale diagram of low, medium and high Earth orbits A high Earth orbit is a geocentric orbit with an altitude entirely above that of a geosynchronous orbit (). The orbital periods of such orbits are greater than 24 hours, therefore satellites in such orbits have an apparent retrograde motion – that is, even if they are in a prograde orbit (90° > inclination ≥ 0°), their orbital velocity is lower than Earth's rotational speed, causing their ground track to move westward on Earth's surface.
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The satellites above the horizontal axis are prograde, the satellites beneath it are retrograde. The yellow segments extend from the pericentre to the apocentre, showing the eccentricity. Neso is about in diameter based on an assumed albedo, and assuming a mean density of 1.5 g/cm3, its mass is estimated at 2 kg. Given the similarity of the orbit's parameters with Psamathe (S/2003 N 1), it was suggested that both irregular satellites could have a common origin in the break-up of a larger moon.
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'Leda , also known as ', is a prograde irregular satellite of Jupiter. It was discovered by Charles T. Kowal at the Mount Palomar Observatory on September 14, 1974, after three nights' worth of photographic plates had been taken (September 11 through 13; Leda appears on all of them). It was named after Leda, who was rapedLeda and the Swan by Zeus, the Greek equivalent of Jupiter (who came to her in the form of a swan). Kowal suggested the name and the IAU endorsed it in 1975.
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Characteristic minerals include andalusite, biotite and cordierite. The metamorphic prograde sequence of the Buchan zone series is: biotite - cordierite - andalusite - sillimanite Buchan metamorphism occurs often in extensional settings, for example at rift basins. In contact metamorphism (metamorphism caused by high temperatures at low pressure in the vicinity of an igneous intrusion) a local contact aureole of zones is formed around a heat source. In rocks in subduction zones, that are transported to great depths in relatively low temperatures, rare types of metamorphic zones can develop.
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Nereid is the third-largest moon of Neptune. It has a prograde but very eccentric orbit and is believed to be a former regular satellite that was scattered to its current orbit through gravitational interactions during Triton's capture. Water ice has been spectroscopically detected on its surface. Early measurements of Nereid showed large, irregular variations in its visible magnitude, which were speculated to be caused by forced precession or chaotic rotation combined with an elongated shape and bright or dark spots on the surface.
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The Gallic group are four prograde outer moons that are similar enough in their distance from the planet (207–302 radii of Saturn), their orbital inclination (35–40°) and their color that they can be considered a group. They are Albiorix, Bebhionn, Erriapus, and Tarvos. The largest among these moons is Albiorix with an estimated size of about 32 km. There is an additional satellite S/2004 S 24 that could belong to this group, but more observations are needed to confirm or disprove its categorization.
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This is in turn overlain by stringy-beef textured recrystallised disseminated ore zones containing retrogressed metamorphic olivine and distinctive bladed anthophyllite. The structural overprint of the ultramafics and orebody by deformation during prograde metamorphism is a matter of debate, however the ductile nature of the deformation has affected the ultramafic CUU heterogenously and contrasts with the felsic footwall. The felsic footwall is subject to a pronounced stretching lineation which increases in intensity to the north. The lineation orientation is a uniform 65 degrees toward 120 degrees.
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Animation of discovery images showing Margaret's motion relative to background stars and galaxies Irregular satellites of Uranus Margaret stands out as the only prograde irregular satellite of Uranus. The diagram illustrates the orbital parameters of Margaret, unique among the irregular satellites of Uranus, with inclination on the vertical axis and the eccentricity of the orbits represented by the segments extending from the pericentre to the apocentre. Margaret's inclination of 57° is close to the limit of stability. The intermediate inclinations 60 < i < 140 are devoid of known moons due to the Kozai instability.
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One group of Jupiter trojans can be depleted relative to the other if the ice giant passes through it following the ice giant's last encounter with Jupiter. Later, when Jupiter and Saturn are near mean-motion resonances, other Jupiter trojans can be captured via the mechanism described in the original Nice model. Other planetesimals are captured as irregular satellites of the giant planets via three-body interactions during encounters between the ejected ice giant and the other planets. The irregular satellites begin with wide range of inclinations including prograde, retrograde, and perpendicular orbits.
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The formation comprises a succession of lenticular bodies showing two main facies; clayey sands rich in frequently pyrite}pyritised lignite, together with amber and grey clayey sands with less lignite (1 to 12 % of the sediment), with continental vertebrate fauna. These facies, the rarity of mollusk shells and charophytes, probably due to decarbonatation and the presence of pyrrhotite (FeS4), reflect a hypoxic environment. The strata were deposited at the bottom of two channels cutting into underlying Thanetian marine green sands. The channels prograde toward the northeast and were discovered under Oise River Quaternary deposits.
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To give precise estimates of the pace of growth of a single garnet crystal, geochronologists use microsampling methods to collect and date small consecutive zones of garnet crystals. Another low-temperature, high-pressure metamorphic index mineral, lawsonite was brought into use in recent years to understand subduction metamorphism using Lu/Hf dating. A study showed that lawsonite could be significant in dating low-temperature metamorphic rocks, typically in prograde metamorphism in a subduction zone settings, as garnets are formed after lawsonite is stabilized, so that lawsonite can be enriched in Lu for radiometric dating.
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In 2013 a double planetary system was detected orbiting around this star from radial velocity measurements at Okayama Astrophysical Observatory and Australian Astronomical Observatory. The planetary system has two giant planets with identical minimum masses of 2.4 times that of Jupiter with orbital periods of 360 days and 2732 days. The maximum mass of the planets cannot exceed 28 times that of Jupiter based on dynamical stability analysis for the system, if the planets are coplanar and prograde. The planetary system of HD 4732 was found to be stable in 2019.
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Pluto may be defined as having retrograde rotation and an axial tilt of 60 degrees, or prograde rotation and a tilt of 120 degrees. Following the latter convention (the right-hand rule), the hemisphere currently in daylight is the northern one, with much of the southern hemisphere in darkness. This is the convention used by the International Astronomical Union (IAU) and the New Horizons team, and their maps put the sunlit hemisphere on top. However, older sources may define Pluto's rotation as retrograde and therefore the sunlit side as the southern hemisphere.
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The orange moon is in a retrograde orbit. If formed in the gravity field of a planet as the planet is forming, a moon will orbit the planet in the same direction as the planet is rotating and is a regular moon. If an object is formed elsewhere and later captured into orbit by a planet's gravity, it can be captured into either a retrograde or prograde orbit depending on whether it first approaches the side of the planet that is rotating towards or away from it. This is an irregular moon.
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Asteroids usually have a prograde orbit around the Sun. Only a few dozen asteroids in retrograde orbits are known. Some asteroids with retrograde orbits may be burnt-out comets, but some may acquire their retrograde orbit due to gravitational interactions with Jupiter.S. Greenstreet, B. Gladman, H. Ngo, M. Granvik, and S. Larson, "Production of Near-earth Asteroids on Retrograde Orbits", The Astrophysical Journal Letters, 749:L39 (5pp), 2012 April 20 Due to their small size and their large distance from Earth it is difficult to telescopically analyse the rotation of most asteroids.
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Barrovian metamorphism takes place during regional metamorphism, caused by crustal thickening in the roots of an orogenic belt (under mountain chains). Barrovian zones are especially easy to recognize in pelitic rocks. The prograde sequence of Barrovian zones is: :chlorite - biotite - garnet - staurolite - kyanite - sillimanite Andalusite crystals in Dalradian metamorphic rock at Boyndie Bay in the Buchan metamorphic zone of north-east Scotland Often only part of the series can be found. Another metamorphic facies series is the Buchan series, that sees a fast increase in temperature but a relatively small increase in pressure.
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A non-inclined orbit is an orbit coplanar with a plane of reference. The orbital inclination is 0° for prograde orbits, and π (180°) for retrograde ones. If the plane of reference is a massive spheroid body's equatorial plane, these orbits are called equatorial; if the plane of reference is the ecliptic plane, they are called ecliptic. As these orbits lack nodes, the ascending node is usually taken to lie in the reference direction (usually the vernal equinox), and thus the longitude of the ascending node is taken to be zero.
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Mercury's sidereal day is about two- thirds of its orbital period, so by the prograde formula its solar day lasts for two revolutions around the Sun – three times as long as its sidereal day. Venus rotates retrograde with a sidereal day lasting about 243.0 Earth days, or about 1.08 times its orbital period of 224.7 Earth days; hence by the retrograde formula its solar day is about 116.8 Earth days, and it has about 1.9 solar days per orbital period. By convention, rotation periods of planets are given in sidereal terms unless otherwise specified.
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Nereid orbits Neptune in the prograde direction at an average distance of , but its high eccentricity of 0.7507 takes it as close as and as far as . Nereid's highly eccentric orbit around Neptune.The unusual orbit suggests that it may be either a captured asteroid or Kuiper belt object, or that it was an inner moon in the past and was perturbed during the capture of Neptune's largest moon Triton. If the latter is true, it may be the only survivor of Neptune's original (pre-Triton capture) set of regular satellites.
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Ijiraq, or Saturn XXII (22), is a small prograde irregular satellite of Saturn. It was discovered by the team of Brett Gladman, John J. Kavelaars, et al. in 2000, and given the temporary designation '.IAUC 7521: S/2000 S 5, S/2000 S 6 November 18, 2000 (discovery)MPEC 2000-Y14: S/2000 S 3, S/2000 S 4, S/2000 S 5, S/2000 S 6, S/2000 S 10 December 19, 2000 (discovery and ephemeris) It was named in 2003 after the ijiraq, a creature in Inuit mythology.
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The metamorphic event has an anticlockwise pressure-temperature-time path with nearly isobaric cooling. The anti-clockwise path indicates the metamorphism is related to the intrusion of magma within the Earth's crust. During prograde and peak metamorphism, temperature and pressure are increased and a large amount of mafic material is added to the crust, whereas after the peak metamorphism, the intrusion of magma stops, resulting in isobaric cooling. Structurally, these Late Neoarchean rocks are dome-shaped, for example, the Jinzhou dome in southern Liaoning and the Huadian dome in southern Jilin.
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Following the encounters, the satellites with inclinations between 60° and 130° are lost due to the Kozai resonance and the more distant prograde satellites are lost to the evection resonance. Collisions among the satellites result in the formation of families, in a significant loss of mass, and in a shift of their size distribution. The populations and orbits of Jupiter's irregular satellites captured in simulations are largely consistent with observations. Himalia, which has a spectra similar to asteroids in the middle of the asteroid belt, is somewhat larger than the largest captured in simulations.
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Geostationary satellites are launched to the east into a prograde orbit that matches the rotation rate of the equator. The smallest inclination that a satellite can be launched into is that of the launch site's latitude, so launching the satellite from close to the equator limits the amount of inclination change needed later. Additionally, launching from close to the equator allows the speed of the Earth's rotation to give the satellite a boost. A launch site should have water or deserts to the east, so any failed rockets do not fall on a populated area.
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Geosynchronous satellites are launched to the east into a prograde orbit that matches the rotation rate of the equator. The smallest inclination that a satellite can be launched into is that of the launch site's latitude, so launching the satellite from close to the equator limits the amount of inclination change needed later. Additionally, launching from close to the equator allows the speed of the Earth's rotation to give the satellite a boost. A launch site should have water or deserts to the east, so any failed rockets do not fall on a populated area.
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As the system later cools and melt crystallizes, regrown monazite will have higher Y content. Partial melting usually happens during peak metamorphism (the highest temperature in a P-T path), but age and chemical information during this stage are not recorded since the monazite is melting. However, the ages of last prograde growth rim (lowest Y) and the first post-anatectic growth rim (highest Y) usually bracket the time of partial melting. Another scenario involves the formation or breakdown of garnet, influencing the Y and HREE (heavy rare earth elements) content in the environment, thus the content of growing monazite.
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Such changes were observed in 2010. Triton's revolution around Neptune has become a nearly perfect circle with an eccentricity of almost zero. Viscoelastic damping from tides alone is not thought to be capable of circularizing Triton's orbit in the time since the origin of the system, and gas drag from a prograde debris disc is likely to have played a substantial role. Tidal interactions also cause Triton's orbit, which is already closer to Neptune than the Moon's is to Earth, to gradually decay further; predictions are that 3.6 billion years from now, Triton will pass within Neptune's Roche limit.
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A quasi- satellite, such as the one shown in this diagram, moves in a prograde orbit around the Sun, with the same orbital period (which we will call a year) as the planet it accompanies, but with a different (usually greater) orbital eccentricity. It appears, when seen from the planet, to revolve around the planet once a year in the retrograde direction, but at varying speed and probably not in the ecliptic plane. Relative to its mean position, moving at constant speed in the ecliptic, the quasi-satellite traces an analemma in the planet's sky, going around it once a year.
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The Plutonian system is highly compact: the five known satellites orbit within the inner 3% of the region where prograde orbits would be stable. The orbital periods of all Pluto's moons are linked in a system of orbital resonances and near resonances. When precession is accounted for, the orbital periods of Styx, Nix, and Hydra are in an exact 18:22:33 ratio. There is a sequence of approximate ratios, 3:4:5:6, between the periods of Styx, Nix, Kerberos, and Hydra with that of Charon; the ratios become closer to being exact the further out the moons are.
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Uranus has an axial tilt of 97.77°, so its axis of rotation is approximately parallel with the plane of the Solar System. The reason for Uranus's unusual axial tilt is not known with certainty, but the usual speculation is that during the formation of the Solar System, an Earth-sized protoplanet collided with Uranus, causing the skewed orientation. It is unlikely that Venus was formed with its present slow retrograde rotation, which takes 243 days. Venus probably began with a fast prograde rotation with a period of several hours much like most of the planets in the Solar System.
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Any such theory needs to explain the following facts: the existence of narrow stable bands and jets that are symmetric relative to Jupiter's equator, the strong prograde jet observed at the equator, the difference between zones and belts, and the origin and persistence of large vortices such as the Great Red Spot.Vasavada (2005), p. 1942–1974 The theories regarding the dynamics of the Jovian atmosphere can be broadly divided into two classes: shallow and deep. The former hold that the observed circulation is largely confined to a thin outer (weather) layer of the planet, which overlays the stable interior.
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As Kepler-8b orbits its star, it demonstrates the Rossiter–McLaughlin effect, in which the host star's spectrum becomes red- and, later, blueshifted, as a body transits it. The identification of this effect established Kepler-8b as orbiting in a prograde motion (as opposed to retrograde motion, in which a planet orbits in a direction opposite of its star's rotation). The study in 2012, have determined the planetary orbit is probably well aligned with the equatorial plane of the star, misalignment equal to 5°. The planet is likely to be tidally locked to the parent star.
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Integrating the above energy equation is often unnecessary if the burn duration is short. Short burns of chemical rocket engines close to periapsis or elsewhere are usually mathematically modelled as impulsive burns, where the force of the engine dominates any other forces that might change the vehicle's energy over the burn. For example, as a vehicle falls towards periapsis in any orbit (closed or escape orbits) the velocity relative to the central body increases. Briefly burning the engine (an “impulsive burn”) prograde at periapsis increases the velocity by the same increment as at any other time (\Delta v).
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The period was supposedly 20.85 days, with prograde motion. Pickering estimated the diameter at , but since he also gave as the diameter of Phoebe, he was clearly overestimating the albedo; using the modern figure for Phoebe gives Themis a diameter of . Two possible orbits for Themis as calculated by W. H. Pickering Oddly, in April 1861, Hermann Goldschmidt had also believed that he had discovered a new satellite of Saturn between Titan and Hyperion, which he called Chiron. Chiron also does not exist (however, the name was used much later for the comet/asteroid 2060 Chiron).
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Borman started the first sleep shift but found sleeping difficult because of the constant radio chatter and mechanical noises. Testing on the ground had shown that the service propulsion system (SPS) engine had a small chance of exploding when burned for long periods unless its combustion chamber was "coated" first by burning the engine for a short period. This first correction burn was only 2.4 seconds and added about velocity prograde (in the direction of travel). This change was less than the planned , because of a bubble of helium in the oxidizer lines, which caused unexpectedly low propellant pressure.
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The feature called Uranus Dark Spot (UDS) moved in the prograde direction relative Uranus's rotation with an average speed of , which is almost faster than the speed of clouds at the same latitude. The latitude of UDS was approximately constant. The feature was variable in size and appearance and was often accompanied by a bright white clouds called Bright Companion (BC), which moved with nearly the same speed as UDS itself. The behavior and appearance of UDS and its bright companion were similar to Neptunian Great Dark Spots (GDS) and their bright companions, respectively, though UDS was significantly smaller.
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The remaining regular moons orbit near the outer edge of the A Ring, within G Ring and between the major moons Mimas and Enceladus. The regular satellites are traditionally named after Titans and Titanesses or other figures associated with the mythological Saturn. The remaining 58, with mean diameters ranging from 4 to 213 km, are irregular satellites, whose orbits are much farther from Saturn, have high inclinations, and are mixed between prograde and retrograde. These moons are probably captured minor planets, or debris from the breakup of such bodies after they were captured, creating collisional families.
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The objects in the Himalia group have semi-major axes (distances from Jupiter) in the range of 11.15 and 11.75 Gm, inclinations between 26.6° and 28.3°, and eccentricities of between 0.11 and 0.25. All orbit prograde. In physical appearance, the group is very homogenous, all satellites displaying neutral colours (colour indices B−V = 0.66 and V−R = 0.36) similar to those of C-type asteroids. Given the limited dispersion of the orbital parameters and the spectral homogeneity, it has been suggested that the group could be a remnant of the break-up of an asteroid from the main asteroid belt.
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Albiorix is a prograde irregular satellite of Saturn. It was discovered by Holman and colleagues in 2000, and given the temporary designation S/2000 S 11.IAUC 7545: S/2000 S 11 19 December 2000 (discovery)MPEC 2000-Y13: S/2000 S 11 19 December 2000 (discovery and ephemeris)Gladman, B. J.; Nicholson, P. D.; Burns, J. A.; Kavelaars, J. J.; Marsden, B. G.; Holman, M. J.; Grav, T.; Hergenrother, C. W.; Petit, J.-M.; Jacobson, R. A.; and Gray, W. J.; Discovery of 12 satellites of Saturn exhibiting orbital clustering, Nature, 412 (July 12, 2001), pp.
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The rotation period of Siarnaq was measured by the Cassini spacecraft to be 10.19 hours; this is the shortest rotation period of all prograde irregular moons of Saturn. Siarnaq displays a light curve with three maxima and minima over a full rotation, implying a roughly triangular shape. From Cassini observations of Siarnaq at different phase angles, the orientation of its north rotational pole has been determined to be pointing toward 98° ecliptic latitude and −23° ecliptic longitude. This corresponds to a sideways axial tilt, indicating that Siarnaq experiences long, extreme seasons similar to the planet Uranus.
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Instead, the new plan was to place the probe in a highly elliptical orbit with an apoapsis of a hundred thousand kilometers and a periapsis of a few thousand kilometers from Venus. Engineers planned for the alternate orbit to be prograde (in the direction of the atmospheric super- rotation) and lie in the orbital plane of Venus. The method and orbit were announced by JAXA in February 2015, with an orbit insertion date of 7 December 2015. The probe reached its most distant point from Venus on 3 October 2013 and had been approaching the planet since then.
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Saturn's Known Satellites The Cassini spacecraft observed Tarqeq over 1.5 days on 15–16 January 2014. The Tarqiup (Tarqeqian)The genitive form of Tarqeq is Tarqiup (as in _Tarqiup_ Inua 'Master _of the Moon_ '). Thus the adjectival form could be absolutive Tarqeqian or genitive Tarqiupian, parallel to nominative Venusian and genitive Venerian for Venus. See Inuktitut morphology orbit lies at an inclination of 49.90° (to the ecliptic; 49.77° to Saturn's equator), with an eccentricity of 0.1081 and a semi-major axis of 17.9106 Gm. Tarqeq orbits in a prograde direction with a period of 894.86 days.
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The piemonte zone, remnant of the Piemontese Ocean from the Late Jurassic, is home to the majority of the serpentines of the Western Alps. The Balangero mine is located in the Lanzu Ultramafic Massif which is in the inner part of the piemonte zone. The Lanzu Ultramafic Massif is believed to have been involved in the subduction processes that were affiliated with the closure of the Piemontese Ocean in the late Jurassic. The earliest generation of metamorphic veins and in particular type 1 Vein that constitute relict prismatic balangeroite (often includes antigorite flakes) were formed during prograde high pressure metamorphism.
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If the position angle of the body's prime meridian increases with time, the body has a direct (or prograde) rotation; otherwise the rotation is said to be retrograde. In the absence of other information, the axis of rotation is assumed to be normal to the mean orbital plane; Mercury and most of the satellites are in this category. For many of the satellites, it is assumed that the rotation rate is equal to the mean orbital period. In the case of the giant planets, since their surface features are constantly changing and moving at various rates, the rotation of their magnetic fields is used as a reference instead.
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Ignoring the influence of other solar system bodies, Earth's orbit is an ellipse with the Earth-Sun barycenter as one focus and a current eccentricity of 0.0167; since this value is close to zero, the center of the orbit is close, relative to the size of the orbit, to the center of the Sun. As seen from Earth, the planet's orbital prograde motion makes the Sun appear to move with respect to other stars at a rate of about 1° eastward per solar day (or a Sun or Moon diameter every 12 hours).Our planet takes about 365 days to orbit the Sun. A full orbit has 360°.
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Most regular moons (natural satellites following relatively close and prograde orbits with small orbital inclination and eccentricity) in the Solar System are tidally locked to their respective primaries, meaning that the same side of the natural satellite always faces its planet. The only known exception is Saturn's natural satellite Hyperion, which rotates chaotically because of the gravitational influence of Titan. In contrast, the outer natural satellites of the giant planets (irregular satellites) are too far away to have become locked. For example, Jupiter's Himalia, Saturn's Phoebe, and Neptune's Nereid have rotation periods in the range of ten hours, whereas their orbital periods are hundreds of days.
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In astronomy, an inner moon or inner natural satellite is a natural satellite following a prograde, low-inclination orbit inwards of the large satellites of the parent planet. They are generally thought to have been formed in situ at the same time as the coalescence of the original planet. Neptune's moons are an exception, as they are likely reaggregates of the pieces of the original bodies, which were disrupted after the capture of the large moon Triton. Inner satellites are distinguished from other regular satellites by their proximity to the parent planet, their short orbital periods (usually under a day), their low mass, small size, and irregular shapes.
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Silver, B. A. (1963) The Bluebonnet Member, Lake Waco Formation (Upper Cretaceous), Central Texas-A lagoonal deposit: Baylor Geologic Studies Bulletin 4, Waco, Texas, 46 p. Following deposition of the calcarenites, a river delta began to prograde from the Ouachita Uplift to the northern East Texas Basin. Although the sandstones and siltstones from this delta, known as the Templeton Member, were originally placed within the Woodbine Formation,Bergquist, H. R. (1949) Geology of the Woodbine Formation of Cooke, Grayson, and Fannin Counties, Texas: USGS, Oil and Gas Investigation, Preliminary Map 98. the ammonites found within them indicate that they are better associated with the Eagle Ford.
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If a satellite in areosynchonous orbit were to be used as a communication relay link, it "would experience communications ranges of " to various points on the visible Martian surface. An areosynchronous orbit that is equatorial (AEO) (in the same plane as the equator of Mars), circular, and prograde (rotating about Mars's axis in the same direction as the planet's surface) is known as an areostationary orbit. To an observer on the surface of Mars, the position of a satellite in AEO would appear to be fixed in a constant position in the sky. The AEO is analogous to a geostationary orbit (GEO) about Earth.
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Tide clock Tide clock Alunatime at Trinity Buoy Wharf, London A tide clock is a specially designed clock that keeps track of the Moon's apparent motion around the Earth. Along many coastlines, the Moon contributes the major part (67%) of the combined lunar and solar tides. The exact interval between tides is influenced by the position of the Moon and Sun relative to the Earth, as well as the specific location on Earth where the tide is being measured. Due to the Moon's orbital prograde motion, it takes a particular point on the Earth (on average) 24 hours and 50.5 minutes to rotate under the Moon, so the time between high lunar tides fluctuates between 12 and 13 hours.
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The Hubble discovery image of Nix and Hydra Discovery image of Styx, overlaid with orbits of the satellite system Pluto's four small circumbinary moons orbit Pluto at two to four times the distance of Charon, ranging from Styx at 42,700 kilometres to Hydra at 64,800 kilometres from the barycenter of the system. They have nearly circular prograde orbits in the same orbital plane as Charon. All are much smaller than Charon. Nix and Hydra, the two larger, are roughly 42 and 55 kilometers on their longest axis respectively, and Styx and Kerberos are 7 and 12 kilometers respectively.New Horizons Picks Up StyxLast of Pluto’s Moons – Mysterious Kerberos – Revealed by New Horizons All four are irregularly shaped.
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The Hill sphere is only an approximation, and other forces (such as radiation pressure or the Yarkovsky effect) can eventually perturb an object out of the sphere. This third object should also be of small enough mass that it introduces no additional complications through its own gravity. Detailed numerical calculations show that orbits at or just within the Hill sphere are not stable in the long term; it appears that stable satellite orbits exist only inside 1/2 to 1/3 of the Hill radius. The region of stability for retrograde orbits at a large distance from the primary is larger than the region for prograde orbits at a large distance from the primary.
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Investigations of photographs and > sightings of the fireball indicated its path through the atmosphere was > probably too steep to be consistent with a spacecraft re-entering from Earth > orbit and was more likely a meteor in a prograde orbit from the vicinity of > the asteroid belt, and probably ended its flight over western Lake Erie. > U.S. Air Force tracking data on Cosmos 96 also indicate the spacecraft orbit > decayed earlier than 21:43 UT on 9 December. Other unconfirmed reports state > the fireball subsequently landed in Pennsylvania southeast of Pittsburgh > near the town of Kecksburg (40.2 N, 79.5 W) at 4:46 p.m. EST (although > estimating the impact point of fireballs from eyewitness accounts is > notoriously inaccurate).
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Dating of garnets with Lu–Hf could provide information of history of garnet growth during prograde metamorphism and peak P-T conditions. With the help of garnet Lu/Hf ages, a study on Lago di Cignana, western Alps, Italy, an age of 48.8±2.1 million yr for lower boundary of garnet growth time was identified. From this, the burial rate of ultra-high-pressure rocks at Lago di Cignana was estimated to be 0.23–0.47 cm/yr, which suggest ocean floor rocks were carried down to subduction and reached ultra-high-pressure metamorphism conditions. Conventional isochron ages are obtained from bulk garnet separates and are only an estimate of the average age of the overall growth of garnet.
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One of those bright cloud features, located at −34° of latitude and called Berg, probably existed continuously since at least 1986. Nevertheless, the Uranian atmosphere has rather strong zonal winds blowing in the retrograde (counter to the rotation) direction near the equator, but switching to the prograde direction poleward of ±20° latitude. The wind speeds are from −50 to −100 m/s at the equator increasing up to 240 m/s near 50° latitude. The wind profile measured before the equinox of 2007 was slightly asymmetric with winds stronger in the southern hemisphere, although it turned out to be a seasonal effect as this hemisphere was continuously illuminated by the Sun before 2007.
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Europa is a very dark carbonaceous C-type, and is the second largest of this group. Spectroscopic studies have found evidence of olivines and pyroxenes on the surface, and there is some indication that there may be compositional differences between different regions It orbits close to the Hygiea asteroid family, but is not a member. Lightcurve data for Europa have been particularly tricky to interpret, so much so that for a long time its period of rotation was in dispute (ranging from 5 and a half hours to 11 hours), despite numerous observations. It has now been determined that Europa is a prograde rotator, but the exact direction in which its pole points remains ambiguous.
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Venus is close enough to the Sun to experience significant gravitational tidal dissipation, and also has a thick enough atmosphere to create thermally driven atmospheric tides that create a retrograde torque. Venus' present slow retrograde rotation is in equilibrium balance between gravitational tides trying to tidally lock Venus to the Sun and atmospheric tides trying to spin Venus in a retrograde direction. In addition to maintaining this present day equilibrium, tides are also sufficient to account for evolution of Venus's rotation from a primordial fast prograde direction to its present-day slow retrograde rotation. In the past, various alternative hypotheses have been proposed to explain Venus' retrograde rotation, such as collisions or it having originally formed that way.
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River mouth bars stagnate, or cease to prograde when the water depth above the flow is shallow enough to create a pressure on the upstream side of the bar strong enough to force the flow around the deposit rather than over the top of the bar. This divergent channel flow around either side of the sediment deposit continuously transports sediment, which over time is deposited on either side of this original mid channel deposit. As more and more sediment accumulates across the mouth of the river, it builds up to eventually create a sand bar that has the potential to extend the entire length of the river mouth and block the flow.
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In astronomy, a regular moon is a natural satellite following a relatively close and prograde orbit with little orbital inclination or eccentricity. They are believed to have formed in orbit about their primary, as opposed to irregular moons, which were captured. There are at least 57 regular satellites of the eight planets: one at Earth, eight at Jupiter, 23 named regular moons at Saturn (not counting hundreds or thousands of moonlets), 18 known at Uranus, and 7 small regular moons at Neptune (Neptune's largest moon Triton appears to have been captured). It is thought that Pluto's five moons and Haumea's two were formed in orbit about those dwarf planets out of debris created in giant collisions.
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Typically, satellites have a roughly sinusoidal ground track. A satellite with an orbital inclination between zero and ninety degrees is said to be in what is called a direct or prograde orbit, meaning that it orbits in the same direction as the Earth's rotation. A satellite with an orbital inclination between 90° and 180° (or, equivalently, between -90° and 0°) is said to be in a retrograde orbit. (Direct orbits are by far the most common for artificial satellites, as the initial velocity imparted by the Earth's rotation at launch reduces the delta-v needed to achieve orbit.) A satellite in a direct orbit with an orbital period less than one day will tend to move from west to east along its ground track.
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Intrusions such as hotspots or rifts at mid-ocean ridges commonly produce metamorphic rocks displaying anticlockwise P-T-t paths patterns with near- isobaric cooling P-T trajectories, and the reason is as follow: # During prograde metamorphism until peak, initial heating and compression until reaching a low pressure-high temperature (LPHT) peak is shown, implying an event of heating generated from below and the crust is slightly thickened. This reflects the action of magma intrusion and erupted as sheet intrusive layer such as sills, resulting in a slight increase in pressure but a great increase in temperature. # During retrograde metamorphism, near-isobaric cooling after the peak took place, indicating that the rock stays at the same position while the magma cools.
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P-T-t paths can be used to estimate possible structures in the field as heat would transfer in small scale advective heat flow during thrusting and folding of metamorphic rocks. For example, during the formation of fault-bend-fold, the rocks in the lower segment (footwall) are heated due to contact with the hotter upper thrust sheet (hanging wall), while the upper thrust sheet is cooling because of losing heat in a downward direction. Thus, the lower segment and the upper thrust sheet are undergoing prograde metamorphism and retrograde metamorphism respectively. Nevertheless, special attention should be taken to the effect of multiple thrusting such as duplexes, where the initial lower plate in an earlier thrust would become the upper plate in a later thrusting event.
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Thermal image of Jupiter obtained by NASA Infrared Telescope Facility The deep model easily explains the strong prograde jet observed at the equator of Jupiter; the jets it produces are stable and do not obey the 2D stability criterion. However it has major difficulties; it produces a very small number of broad jets, and realistic simulations of 3D flows are not possible as of 2008, meaning that the simplified models used to justify deep circulation may fail to catch important aspects of the fluid dynamics within Jupiter. One model published in 2004 successfully reproduced the Jovian band- jet structure. It assumed that the molecular hydrogen mantle is thinner than in all other models; occupying only the outer 10% of Jupiter's radius.
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This epoch causes the roughly 30 Indian calendar years to begin 23–28 days after the modern vernal equinox. The vernal equinox of the Surya Siddhanta librated 27° in both directions from the sidereal epoch. Thus the equinox moved 54° in one direction and then back 54° in the other direction. This cycle took 7200 years to complete at a rate of 54″/year. The equinox coincided with the epoch at the beginning of the Kaliyuga in −3101 and again 3600 years later in 499. The direction changed from prograde to retrograde midway between these years at −1301 when it reached its maximum deviation of 27°, and would have remained retrograde, the same direction as modern precession, for 3600 years until 2299.
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In order of their distance from the planet, the irregular moons are Triton, Nereid, Halimede, Sao, Laomedeia, Psamathe, and Neso, a group that includes both prograde and retrograde objects. The five outermost moons are similar to the irregular moons of other giant planets, and are thought to have been gravitationally captured by Neptune, unlike the regular satellites, which probably formed in situ. Triton and Nereid are unusual irregular satellites and are thus treated separately from the other five irregular Neptunian moons, which are more like the outer irregular satellites of the other outer planets. Firstly, they are the largest two known irregular moons in the Solar System, with Triton being almost an order of magnitude larger than all other known irregular moons.
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In 1975, the International Astronomical Union's (IAU) Task Group for Outer Solar System Nomenclature granted names to satellites V–XIII, and provided for a formal naming process for future satellites still to be discovered. The practice was to name newly discovered moons of Jupiter after lovers and favorites of the god Jupiter (Zeus) and, since 2004, also after their descendants.Gazetteer of Planetary Nomenclature Planet and Satellite Names and Discoverers International Astronomical Union (IAU) All of Jupiter's satellites from XXXIV (Euporie) onward are named after descendants of Jupiter or Zeus, except LIII (Dia), named after a lover of Jupiter. Names ending with "a" or "o" are used for prograde irregular satellites (the latter for highly inclined satellites), and names ending with "e" are used for retrograde irregulars.
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Extreme mass ratio inspirals (EMRIs) consist of a stellar compact object (<60 solar masses) on a slowly decaying orbit around a massive black hole of around 105 solar masses. For the ideal case of a prograde orbit around a (nearly) maximally spinning black hole, LISA will be able to detect these events up to z=4. EMRIs are interesting because they are slowly evolving, spending around 105 orbits and between a few months and a few years in the LISA sensitivity band before merging. This allows very accurate (up to an error of 1 in 104) measurements of the properties of the system, including the mass and spin of the central object and the mass and orbital elements (eccentricity and inclination) of the smaller object.
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Kiviuq is a prograde irregular satellite of Saturn. It was discovered by J. J. KavelaarsKavelaars, J. J., et al. The discovery of faint irregular satellites of Uranus Icarus 169 (2004), 474. in 2000, and given the temporary designation S/2000 S 5.IAUC 7521: S/2000 S 5, S/2000 S 6 November 18, 2000 (discovery)MPEC 2000-Y14: S/2000 S 3, S/2000 S 4, S/2000 S 5, S/2000 S 6, S/2000 S 10 December 19, 2000 (discovery and ephemeris) It was named after Kiviuq, a hero of Inuit mythology.IAUC 8177: Satellites of Jupiter, Saturn, Uranus August 8, 2003 (naming the moon) Kiviuq is about in diameter, and orbits Saturn at an average distance of 11.1 million kilometers in 450 days.
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Despite being closer to the Sun than Venus, Mercury is not tidally locked because it has entered a 3:2 spin–orbit resonance due to the eccentricity of its orbit. Mercury's prograde rotation is slow enough that due to its eccentricity, its angular orbital velocity exceeds its angular rotational velocity near perihelion, causing the motion of the sun in Mercury's sky to temporarily reverse. The rotations of Earth and Mars are also affected by tidal forces with the Sun, but they have not reached an equilibrium state like Mercury and Venus because they are further out from the Sun where tidal forces are weaker. The gas giants of the Solar System are too massive and too far from the Sun for tidal forces to slow down their rotations.
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Prograde metamorphism to either greenschist facies or amphibolite facies tends to revert igneous olivine to metamorphic olivine, serpentinite or talc carbonated ultramafic schists. In the ore environment, the metamorphism tends to remobilise the nickel sulfide which, during peak metamorphism, has the yield strength and behaviour of toothpaste as conceptualised by workers within the field. The massive sulfides tend to move tens to hundreds of meters away from their original depositional position into fold hinges, footwall sediments, faults or become caught up within asymmetric shear zones. While sulfide minerals do not change their mineralogy during metamorphism as silicates do, the yield strength of the nickel sulfide pentlandite, and copper sulfide chalcopyrite is less than that of pyrrhotite and pyrite, resulting in a potential to segregate the sulfides mechanically throughout a shear zone.
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Cox starts this episode in Al-Qayrawan, Tunisia to analyse the orbit of the planets around our Sun, with details on how the 23 degree tilt of the Earth creates the seasonal weather patterns. He also visits the Atlas Mountains, and relates how in clear night skies the ancients observed the rotation of the stars and the retrograde and prograde motion of Mars and the other wandering planets. In Oklahoma, US, he discusses the universal reach of the Coriolis effect and the importance of the conservation of angular momentum. Next, at the Jet Propulsion Laboratory he examines how the Cassini–Huygens space-probe's imagery provides an insight on the highly complex structure of the ice rings of Saturn, and its diverse array of moons, and how they can reveal insights into the formation and evolution of the Solar System.
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The reason could be that migration might become inefficient near the critical radius, leaving planets just outside this radius.Recent Kepler Results On Circumbinary Planets, William F. Welsh, Jerome A. Orosz, Joshua A. Carter, Daniel C. Fabrycky, (Submitted on 28 Aug 2013) For example, Kepler-47c is a gas giant in the circumbinary habitable zone of the Kepler-47 system. If Earth-like planets form in or migrate into the circumbinary habitable zone they are capable of sustaining liquid water on their surface in spite of the dynamical and radiative interaction with the binary star. The limits of stability for S-type and P-type orbits within binary as well as triple stellar systems have been established as a function of the orbital characteristics of the stars, for both prograde and retrograde motions of stars and planets.
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In celestial mechanics, the Kozai mechanism or Lidov–Kozai mechanism or Kozai–Lidov mechanism, also known as the Kozai, Lidov–Kozai or Kozai–Lidov effect, oscillations, cycles or resonance, is a dynamical phenomenon affecting the orbit of a binary system perturbed by a distant third body under certain conditions, causing the orbit's argument of pericenter to oscillate about a constant value, which in turn leads to a periodic exchange between its eccentricity and inclination. The process occurs on timescales much longer than the orbital periods. It can drive an initially near-circular orbit to arbitrarily high eccentricity, and flip an initially moderately inclined orbit between a prograde and a retrograde motion. The effect has been found to be an important factor shaping the orbits of irregular satellites of the planets, trans-Neptunian objects, extrasolar planets, and multiple star systems.
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Dione occults Enceladus The natural satellites orbiting relatively close to the planet on prograde, uninclined circular orbits (regular satellites) are generally thought to have been formed out of the same collapsing region of the protoplanetary disk that created its primary. In contrast, irregular satellites (generally orbiting on distant, inclined, eccentric and/or retrograde orbits) are thought to be captured asteroids possibly further fragmented by collisions. Most of the major natural satellites of the Solar System have regular orbits, while most of the small natural satellites have irregular orbits.Encyclopedia of the Solar System, page 366, Academic Press, 2007, Lucy-Ann Adams McFadden, Paul Robert Weissman, Torrence V. Johnson The Moon and possibly Charon are exceptions among large bodies in that they are thought to have originated by the collision of two large proto-planetary objects (see the giant impact hypothesis).
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Eros asteroid from approximately 250 meters altitude (area in image is roughly 12 meters across ). This image was taken during NEAR's descent to the surface of the asteroid. Following the flyby NEAR moved to a 200 km circular orbit and shifted the orbit from prograde near-polar to a retrograde near-equatorial orbit. By December 13, 2000 the orbit was shifted back to a circular 35 km low orbit. Starting on January 24, 2001 the spacecraft began a series of close passes (5 to 6 km) to the surface and on January 28 passed 2 to 3 km from the asteroid. The spacecraft then made a slow controlled descent to the surface of Eros ending with a touchdown just to the south of the saddle-shaped feature Himeros on February 12, 2001 at approximately 20:01 UT (3:01 p.m. EST).
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As of 2012, data is available for less than 200 asteroids and the different methods of determining the orientation of poles often result in large discrepancies. The asteroid spin vector catalog at Poznan Observatory avoids use of the phrases "retrograde rotation" or "prograde rotation" as it depends which reference plane is meant and asteroid coordinates are usually given with respect to the ecliptic plane rather than the asteroid's orbital plane.Documentation for Asteroid Spin Vector Determinations Asteroids with satellites, also known as binary asteroids, make up about 15% of all asteroids less than 10 km in diameter in the main belt and near-Earth population and most are thought to be formed by the YORP effect causing an asteroid to spin so fast that it breaks up.Kevin J. Walsh, Derek C. Richardson & Patrick Michel, "Rotational breakup as the origin of small binary asteroids", Nature, Vol.
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Until this time it was usually simply known as "the satellite of Neptune". Other moons of Neptune are also named for Greek and Roman water gods, in keeping with Neptune's position as god of the sea: either from Greek mythology, usually children of Poseidon, the Greek Neptune (Triton, Proteus, Despina, Thalassa); lovers of Poseidon (Larissa); classes of minor Greek water deities (Naiad, Nereid); or specific Nereids (Halimede, Galatea, Neso, Sao, Laomedeia, Psamathe). The most recently discovered moon, Hippocamp, was left unnamed from 2013 until 2019, when it was named after the Hippocamp, a mythological creature that was half horse and half fish. For the "normal" irregular satellites, the general convention is to use names ending in "a" for prograde satellites, names ending in "e" for retrograde satellites, and names ending in "o" for exceptionally inclined satellites, exactly like the convention for the moons of Jupiter.
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Erriapus , or Saturn XXVIII (28), is a prograde irregular satellite of Saturn. It was discovered by Brett Gladman, John J. Kavelaars and colleagues in 2000, and given the temporary designation S/2000 S 10.IAUC 7539: S/2000 S 10 December 7, 2000 (discovery)MPEC 2000-Y14: S/2000 S 3, S/2000 S 4, S/2000 S 5, S/2000 S 6, S/2000 S 10 December 19, 2000 (discovery and ephemeris) It was named Erriapo in August 2003IAUC 8177: Satellites of Jupiter, Saturn, Uranus August 8, 2003 (naming the moon) after Erriapus (also rendered Erriappus), a giant in Gaulish mythology; the name was changed from dative Erriapo to nominative Erriapus per IAU conventions in late 2007.IAUC 9191: SATURN XXVIII (ERRIAPUS) January 11, 2011 Erriapus is about 10 kilometres in diameter, and orbits Saturn at an average distance of 17,3 Gm in 871 days.
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The relativistic jet of matter emerging from the core extends at least from the nucleus and consists of matter ejected from a supermassive black hole. The jet is highly collimated, appearing constrained to an angle of 60° within of the core, to about 16° at , and to 6–7° at . Its base has the diameter of Schwarzschild radii, and is probably powered by a prograde accretion disk around the spinning supermassive black hole. The German-American astronomer Walter Baade found that light from the jet was plane polarized, which suggests that the energy is generated by the acceleration of electrons moving at relativistic velocities in a magnetic field. The total energy of these electrons is estimated at 5.1 × 1056 ergs (5.1 × 1049 joules or 3.2 × 1068 eV). This is roughly 1013 times the energy produced by the Milky Way in one second, which is estimated at 5 × 1036 joules.
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All Kepler circumbinary planets that were known as of August 2013 orbit their stars very close to the plane of the binary (in a prograde direction) which suggests a single-disk formation. However, not all circumbinary planets are co-planar with the binary: Kepler-413b is tilted 2.5 degrees which may be due to the gravitational influence of other planets or a third star.Kepler-413b: a slightly misaligned, Neptune-size transiting circumbinary planet, Veselin B. Kostov, Peter R. McCullough, Joshua A. Carter, Magali Deleuil, Rodrigo F. Diaz, Daniel C. Fabrycky, Guillaume Hebrard, Tobias C. Hinse, Tsevi Mazeh, Jerome A. Orosz, Zlatan I. Tsvetanov, William F. Welsh, (Submitted on 28 Jan 2014) Taking into account the selection biases, the average mutual inclination between the planetary orbits and the stellar binaries is within ~3 degrees, consistent with the mutual inclinations of planets in multi-planetary systems.
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Areas with collision-related tectonic events or under subduction zones commonly produce metamorphic rocks with clockwise P-T-t paths with near- isothermal decompressional P-T trajectories, and the reason is as follows: #During prograde metamorphism until peak, initial heating and compression until arriving a high pressure-low temperature (HPLT) peak is shown, suggesting an early phase of progressing burial due to crustal thickening without receiving much heat. #At stage 1 retrograde metamorphism, near- isothermal decompression after the peak, which indicates uplift and exhumation of the compressed rock in the orogenic belt or forearc. # At stage 2 retrograde metamorphism, further decompression and cooling occur at a slow rate, implying further erosion after the tectonic event. In addition, recent studies based on mechanical analysis reveal that peak pressure recorded in clockwise P-T paths does not necessarily represent the maximum depth of burial, but can also represent a change in the tectonic pattern.
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The Solar System's planets, and its most likely dwarf planets, are known to be orbited by at least 218 natural satellites, or moons. 19 of them are large enough to be gravitationally rounded; of these, all are covered by a crust of ice except for Earth's Moon and Io.Ice in the Solar System - NASA Several of the largest ones are in hydrostatic equilibrium and would therefore be considered dwarf planets or planets if they were in direct orbit around the Sun and not in their current states (orbiting planets or dwarf planets). Moons are classed in two separate categories according to their orbits: regular moons, which have prograde orbits (they orbit in the direction of their planets' rotation) and lie close to the plane of their equators, and irregular moons, whose orbits can be pro- or retrograde (against the direction of their planets' rotation) and often lie at extreme angles to their planets' equators. Irregular moons are probably minor planets that have been captured from surrounding space.
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