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Trojan (astronomy)
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 ( ... [...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 Italian and naturalized French mathematician, physicist and astronomer. He made significant contributions to the fields of mathematical analysis, analysis, number theory, and both classical mechanics, classical and celestial mechanics. In 1766, on the recommendation of Leonhard Euler and Jean le Rond d'Alembert, d'Alembert, Lagrange succeeded Euler as the director of mathematics at the Prussian Academy of Sciences in Berlin, Prussia, where he stayed for over twenty y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2013 ND15
is a small asteroid that is a temporary trojan of Venus. Located at Venus's , it is the first known Venus trojan. Discovery, orbit and physical properties was discovered on 13 July 2013 by N. Primak, A. Schultz, T. Goggia and K. Chambers, observing for the Pan-STARRS project. As of September 2014, it has been observed 21 times with a data-arc span of 26 days. It is an Aten asteroid and its semi-major axis (0.7235 astronomical units; AU) is very similar to that of Venus but it has high eccentricity (0.6115) and small orbital inclination (4.794°). With an absolute magnitude of 24.1, it has a diameter in the range 40–100 m (for an assumed albedo range of 0.04–0.20). Trojan dynamical state and orbital evolution has been identified as a Venus trojan following a tadpole orbit around Venus's Lagrangian point . Besides being a Venus co-orbital, this asteroid is also a Mercury crosser and an Earth crosser. exhibits resonant (or near-resonant) behavior with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three-body Problem
In physics, specifically classical mechanics, the three-body problem is to take the initial positions and velocities (or momenta) of three point masses orbiting each other in space and then calculate their subsequent trajectories using Newton's laws of motion and Newton's law of universal gravitation. Unlike the two-body problem, the three-body problem has no general closed-form solution, meaning there is no equation that always solves it. When three bodies orbit each other, the resulting dynamical system is chaotic for most initial conditions. Because there are no solvable equations for most three-body systems, the only way to predict the motions of the bodies is to estimate them using numerical methods. The three-body problem is a special case of the -body problem. Historically, the first specific three-body problem to receive extended study was the one involving the Earth, the Moon, and the Sun. In an extended modern sense, a three-body problem is any problem in cl ... [...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 Italian and naturalized French mathematician, physicist and astronomer. He made significant contributions to the fields of mathematical analysis, analysis, number theory, and both classical mechanics, classical and celestial mechanics. In 1766, on the recommendation of Leonhard Euler and Jean le Rond d'Alembert, d'Alembert, Lagrange succeeded Euler as the director of mathematics at the Prussian Academy of Sciences in Berlin, Prussia, where he stayed for over twenty y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomer
An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers 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 typically 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 Con ... [...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, mathematical structure, structure, space, Mathematical model, models, and mathematics#Calculus and analysis, change. History One of the earliest known mathematicians was Thales of Miletus (); 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's theorem. The number of known mathematicians grew when Pythagoras of Samos () 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 math ... [...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] |
Polydeuces (moon)
Polydeuces , also designated Saturn XXXIV, is a small trojan moon of Saturn occupying the trailing Lagrange point of Dione. It was discovered by the Cassini Imaging Science Team in images taken by the ''Cassini'' space probe on 21 October 2004. With a mean diameter of about , Polydeuces is thought to have a smooth surface coated with fine, icy particles accumulated from the cryovolcanic plumes of Enceladus. In its orbit around Saturn, Polydeuces periodically drifts away from Dione's Lagrange point due to gravitational perturbations by other nearby moons of Saturn. Of the four known trojan moons of Saturn, Polydeuces exhibits the largest displacement from its Lagrange point. Discovery Polydeuces was discovered by the Cassini Imaging Science Team on 24 October 2004 while routinely investigating images taken by the '' Cassini'' space probe earlier on 21 October 2004. The images were visually inspected through the blink comparison technique, which revealed any potentia ... [...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 li ... [...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] |
Calypso (moon)
__NOTOC__ Calypso is a moon of Saturn. It was discovered in 1980, from ground-based observations, by Dan Pascu, P. Kenneth Seidelmann, William A. Baum, and Douglas G. Currie, and was provisionally designated (the 25th satellite of Saturn discovered in 1980). Several other apparitions of it were recorded in the following months: , , , and . In 1983 it was officially named after Calypso of Greek mythology. It is also designated or Tethys C. Calypso is co-orbital with the moon Tethys, and resides in Tethys's trailing Lagrangian point (), 60 degrees behind Tethys. This relationship was first identified by Seidelmann ''et al.'' in 1981. The moon Telesto resides in the other (leading) Lagrangian point of Tethys, 60 degrees in the other direction from Tethys. Calypso and Telesto have been termed "Tethys trojans", by analogy to the trojan asteroids, and are half of the four presently known trojan moons. Like many other small Saturnian moons and small asteroids, Calypso is irregu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
