|
Trojan Moons
In astronomy, a co-orbital configuration is a configuration of two or more astronomical objects (such as asteroids, moons, or planets) orbiting at the same, or very similar, distance from their primary; i.e., they are in a 1:1 mean-motion resonance. (or 1:-1 if orbiting in opposite directions). There are several classes of co-orbital objects, depending on their point of libration. The most common and best-known class is the trojan, which librates around one of the two stable Lagrangian points (Trojan points), and , 60° ahead of and behind the larger body respectively. Another class is the horseshoe orbit, in which objects librate around 180° from the larger body. Objects librating around 0° are called quasi-satellites. An exchange orbit occurs when two co-orbital objects are of similar masses and thus exert a non-negligible influence on each other. The objects can exchange semi-major axes or eccentricities when they approach each other. Parameters Orbital parameters that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, natural satellite, moons, stars, nebulae, galaxy, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond atmosphere of Earth, Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole. Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Egyptian astronomy, Egyptians, Babylonian astronomy, Babylonians, Greek astronomy, Greeks, Indian astronomy, Indians, Chinese astronomy, Chinese, Maya civilization, M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean Anomaly
In celestial mechanics, the mean anomaly is the fraction of an elliptical orbit's period that has elapsed since the orbiting body passed periapsis, expressed as an angle which can be used in calculating the position of that body in the classical two-body problem. It is the angular distance from the pericenter which a fictitious body would have if it moved in a circular orbit, with constant speed, in the same orbital period as the actual body in its elliptical orbit. Definition Define as the time required for a particular body to complete one orbit. In time , the radius vector sweeps out 2 radians, or 360°. The average rate of sweep, , is then n = \frac = \frac~, which is called the '' mean angular motion'' of the body, with dimensions of radians per unit time or degrees per unit time. Define as the time at which the body is at the pericenter. From the above definitions, a new quantity, , the ''mean anomaly'' can be defined M = n\,(t - \tau) ~, which gives an angul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telesto (moon)
Telesto is a moon of Saturn. It was discovered by Smith, Reitsema, Larson and Fountain in 1980 from ground-based observations, and was provisionally designated . In the following months, several other apparitions were observed: , , and . In 1983 it was officially named after Telesto of Greek mythology. It is also designated as or Tethys B. Telesto is co-orbital with Tethys, residing in Tethys's leading Lagrangian point (). This relationship was first identified by Seidelmann ''et al.'' in 1981. Another moon, Calypso, resides in the other (trailing) Lagrangian point of Tethys, 60 degrees in the other direction from Tethys. The Saturnian system has two additional trojan moons. It eclipsed Tethys in 2024. Exploration The '' Cassini'' probe performed a distant flyby of Telesto on October 11, 2005. The resulting images show that its surface is surprisingly smooth, devoid of small impact crater An impact crater is a depression (geology), depression in the surface o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dione (moon)
Dione (), also designated Saturn IV, is the fourth-largest moon of Saturn. With a mean diameter of 1,123 km and a density of about 1.48 g/cm3, Dione is composed of an icy mantle and crust overlying a silicate rocky core, with rock and water ice roughly equal in mass. Its trailing hemisphere is marked by large cliffs and scarps called chasmata; the trailing hemisphere is also significantly darker compared to the leading hemisphere. The moon was discovered by Italian astronomer Giovanni Domenico Cassini in 1684 and is named after the Titaness Dione in Greek mythology. Dione was first imaged up-close by the ''Voyager 1'' space probe in 1980. Later, the '' Cassini'' spacecraft made multiple flybys of Dione throughout the 2000s and 2010s as part of its campaign to explore the Saturn system. Name Giovanni Domenico Cassini named the four moons he discovered ( Tethys, Dione, Rhea, and Iapetus) '' Sidera Lodoicea'' ("the stars of Louis") to honor king Louis XIV. Cassini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tethys (moon)
Tethys (), or Saturn III, is the fifth-largest moon of Saturn, measuring about across. It was discovered by Giovanni Domenico Cassini in 1684, and is named after the titan Tethys of Greek mythology. Tethys has a low density of 0.98 g/cm3, the lowest of all the major moons in the Solar System, indicating that it is made of water ice with just a small fraction of rock. This was confirmed by the spectroscopy of its surface, which identified water ice as the dominant surface material. A further, smaller amount of an unidentified dark material is present as well. The surface of Tethys is very bright, the second-brightest of the moons of Saturn after Enceladus, and neutral in color. Tethys is heavily cratered and cut by a number of large faults and trench-like graben. The largest impact crater, Odysseus, is about 400 km in diameter, whereas the largest graben, Ithaca Chasma, is about 100 km wide and more than 2,000 km long; the two surface features may be re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
(614689) 2020 XL5
(provisional designation ) is a near-Earth asteroid and Earth trojan discovered by the Pan-STARRS 1 survey at Haleakala Observatory, Hawaii on 12 December 2020. It Tadpole orbit, oscillates around the Sun–Earth Lagrangian point (leading 60°), one of the dynamically stable locations where the combined gravitational force acts through the Sun's and Earth's barycenter. Analysis of 's Trojan (astronomy), trojan orbit stability suggests it will remain around Earth's point for at least four thousand years until gravitational perturbation (astronomy), perturbations from repeated close encounters with Venus destabilize its trojan configuration. With a diameter about , is the second Earth trojan discovered, after , and is the largest of its kind known. Discovery was discovered by the Pan-STARRS 1 survey at Haleakala Observatory, Hawaii on 12 December 2020. It was first observed in the constellation Crater (constellation), Crater at an apparent magnitude of 21.4. The asteroid wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
