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Trojan (celestial Body)
In astronomy, a trojan is a small celestial body (mostly asteroids) that shares the orbit of a larger body, remaining in a stable orbit approximately 60° ahead of or behind the main body near one of its Lagrangian points and . Trojans can share the orbits of planets or of large moons. Trojans are one type of co-orbital object. In this arrangement, a star and a planet orbit about their common barycenter, which is close to the center of the star because it is usually much more massive than the orbiting planet. In turn, a much smaller mass than both the star and the planet, located at one of the Lagrangian points of the star–planet system, is subject to a combined gravitational force that acts through this barycenter. Hence the smallest object orbits around the barycenter with the same orbital period as the planet, and the arrangement can remain stable over time. In the Solar System, most known trojans share the orbit of Jupiter. They are divided into the Greek camp at (ahe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lagrange Very Massive
Joseph-Louis Lagrange (born Giuseppe Luigi LagrangiaJoseph-Louis Lagrange, comte de l’Empire ''Encyclopædia Britannica'' or Giuseppe Ludovico De la Grange Tournier; 25 January 1736 – 10 April 1813), also reported as Giuseppe Luigi Lagrange or Lagrangia, was an and , later naturalized |
Trojan Moon
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] |
Jupiter Trojan
The Jupiter trojans, commonly called trojan asteroids or simply trojans, are a large group of asteroids that share the planet Jupiter's orbit around the Sun. Relative to Jupiter, each trojan librates around one of Jupiter's stable Lagrange points: either ', existing 60° ahead of the planet in its orbit, or ', 60° behind. Jupiter trojans are distributed in two elongated, curved regions around these Lagrangian points with an average semi-major axis of about 5.2 AU. The first Jupiter trojan discovered, 588 Achilles, was spotted in 1906 by German astronomer Max Wolf. More than 9,800 Jupiter trojans have been found . By convention, they are each named from Greek mythology after a figure of the Trojan War, hence the name "trojan". The total number of Jupiter trojans larger than 1 km in diameter is believed to be about , approximately equal to the number of asteroids larger than 1 km in the asteroid belt. Like main-belt asteroids, Jupiter trojans form families. , man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three-body Problem
In physics and classical mechanics, the three-body problem is the problem of taking the initial positions and velocities (or momenta) of three point masses and solving for their subsequent motion according to Newton's laws of motion and Newton's law of universal gravitation. The three-body problem is a special case of the n-body problem, -body problem. Unlike two-body problems, no general closed-form solution exists, as the resulting dynamical system is chaos theory, chaotic for most initial conditions, and numerical methods are generally required. Historically, the first specific three-body problem to receive extended study was the one involving the Moon, Earth, and the Sun. In an extended modern sense, a three-body problem is any problem in classical mechanics Classical mechanics is a physical theory describing the motion of macroscopic objects, from projectiles to parts of machinery, and astronomical objects, such as spacecraft, planets, stars, and galaxies. For o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph-Louis Lagrange
Joseph-Louis Lagrange (born Giuseppe Luigi LagrangiaJoseph-Louis Lagrange, comte de l’Empire ''Encyclopædia Britannica'' or Giuseppe Ludovico De la Grange Tournier; 25 January 1736 – 10 April 1813), also reported as Giuseppe Luigi Lagrange or Lagrangia, was an and , later naturalized [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomer
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, galaxies – in either observational astronomy, observational (by analyzing the data) or theoretical astronomy. Examples of topics or fields astronomers study include planetary science, Sun, solar astronomy, the Star formation, origin or stellar evolution, evolution of stars, or the galaxy formation and evolution, formation of galaxies. A related but distinct subject is physical cosmology, which studies the Universe as a whole. Types Astronomers usually fall under either of two main types: observational astronomy, observational and theoretical astronomy, theoretical. Observational astronomers make direct observations of Astronomical object, celestial objects and analyze the data. In contrast, theoretical astronomers create and investigate C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History One of the earliest known mathematicians were Thales of Miletus (c. 624–c.546 BC); he has been hailed as the first true mathematician and the first known individual to whom a mathematical discovery has been attributed. He is credited with the first use of deductive reasoning applied to geometry, by deriving four corollaries to Thales' Theorem. The number of known mathematicians grew when Pythagoras of Samos (c. 582–c. 507 BC) established the Pythagorean School, whose doctrine it was that mathematics ruled the universe and whose motto was "All is number". It was the Pythagoreans who coined the term "mathematics", and with whom the study of mathematics for its own sake begins. The first woman mathematician recorded by history was Hypati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dione (moon)
Dione () is a moon of Saturn. It was discovered by Italian astronomer Giovanni Domenico Cassini in 1684. It is named after the Titaness Dione of Greek mythology. It is also designated Saturn IV. 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 found Dione in 1684 using a large aerial telescope he set up on the grounds of the Paris Observatory. The satellites of Saturn were not named until 1847, when William Herschel's son John Herschel published ''Results of Astronomical Observations made at the Cape of Good Hope,'' suggesting that the names of the Titans (sisters and brothers of Cronus) be used. Orbit Dione orbits Saturn with a semimajor axis about 2% less than that of the Moon. However, reflecting Saturn's greater mass (95 times that of Earth), Dione's orbital period is one tenth that of the Moon. Dione is currently in a 1:2 mean-motion or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polydeuces (moon)
Polydeuces , or Saturn XXXIV, is a small natural satellite of Saturn that is co-orbital with the moon Dione and librates around its trailing Lagrangian point (). Its diameter is estimated to be 2–3 km. Dione's other co-orbital moon is Helene, which is bigger and located at the leading L4 point. Polydeuces was discovered by thCassini Imaging Team on October 24, 2004, in images taken on October 21, 2004, and given the temporary designation S/2004 S 5. Subsequent searches of earlier ''Cassini'' imaging showed it in images as far back as April 9, 2004. Of the four known Lagrangian co-orbitals in the Saturn system ('trojan moon'), Polydeuces wanders the farthest from its Lagrangian point: its distance behind Dione varies from 33.9° to 91.4° with a period of 790.931 days (for comparison, trails Dione by 60°). Polydeuces's libration is large enough that it takes on some qualities of a tadpole orbit, as evidenced by the clear asymmetry between excursion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helene (moon)
Helene is a moon of Saturn. It was discovered by Pierre Laques and Jean Lecacheux in 1980 from ground-based observations at Pic du Midi Observatory, and was designated . In 1988 it was officially named after Helen of Troy, who was the granddaughter of Cronus (Saturn) in Greek mythology. Helene is also designated (12), which it was given in 1982, and Dione B,Transactions of the International Astronomical Union, Vol. XVIIIA, 1982 (mentioned in IAUC 3872: ''Satellites of Jupiter and Saturn'', September 30, 1983 because it is co-orbital with Dione and located in its leading Lagrangian point (). It is one of four known trojan moons. Exploration Helene was initially observed from Earth in 1980, and '' Voyager'' flybys of Saturn in the early 1980s allowed much closer views. The ''Cassini–Huygens'' mission, which went into orbit around Saturn in 2004, provided still better views, and allowed more in-depth analysis of Helene, including views of the surface under different light ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tethys (moon)
Tethys (), or Saturn III, is a mid-sized moon of Saturn about across. It was discovered by G. D. 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 is confirmed by the spectroscopy of its surface, which identified water ice as the dominant surface material. A small amount of an unidentified dark material is present as well. The surface of Tethys is very bright, being 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/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 2000 km long. These two largest surface features may be related. A small part of the surface is covered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
