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Pasiphae Group
The Pasiphae group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Pasiphae and are thought to have a common origin. Their semi-major axes (distances from Jupiter) range between 22.8 and 24.1 million km (the same range as the Carme group), their inclinations between 144.5° and 158.3°, and their eccentricities between 0.25 and 0.43. Core members of the group include (negative periods indicate retrograde orbits):Scott S. Sheppard, David C. Jewitt, Carolyn Porco ''Jupiter's outer satellites and Trojans'', In: ''Jupiter. The planet, satellites and magnetosphere.'' Edited by Fran Bagenal, Timothy E. Dowling, William B. McKinnon. Cambridge planetary science, Vol. 1, Cambridge, UK: Cambridge University Press, , 2004, p. 263 - 28Full text(pdf). The International Astronomical Union (IAU) reserves names ending in -e for all retrograde moons. Origin The Pasiphae group is believed to have been formed when Jupiter captured an asteroid which subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retrograde Motion
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. The direction of rotation is determined by an inertial frame of reference, such as distant fixed stars. In the Solar System, the orbits around the Sun of all planets and most other objects, except many comets, are prograde. They orbit around the Sun in the same direction as the sun rotates about its axis, which is counterclockwise when observed from above the Sun's north pole. Except for Venus and Uranus, planetary rotations around their axes are also prograde. Most natural satellites have prograde or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autonoe (moon)
Autonoe , also known as , is a natural satellite of Jupiter. Autonoe was discovered by a team of astronomers from the University of Hawaii led by Scott S. Sheppard in 2001, and given the temporary designation .MPEC 2002-J54: ''Eleven New Satellites of Jupiter'' 2002 May 15 (discovery and ephemeris) Autonoe is about 4 kilometres in diameter, and orbits Jupiter at an average distance of 24,264,000 km in 719.01 days. It orbits at an of 151° to the (150° to Jupiter's equator) in a [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moons Of Jupiter
There are 82 known moons of Jupiter, not counting a number of moonlets likely shed from the inner moons. All together, they form a satellite system which is called the Jovian system. The most massive of the moons are the four Galilean moons: Io, Europa, Ganymede, and Callisto, which were independently discovered in 1610 by Galileo Galilei and Simon Marius and were the first objects found to orbit a body that was neither Earth nor the Sun. Much more recently, beginning in 1892, dozens of far smaller Jovian moons have been detected and have received the names of lovers (or other sexual partners) or daughters of the Roman god Jupiter or his Greek equivalent Zeus. The Galilean moons are by far the largest and most massive objects to orbit Jupiter, with the remaining 78 known moons and the rings together composing just 0.003% of the total orbiting mass. Of Jupiter's moons, eight are regular satellites with prograde and nearly circular orbits that are not greatly inclined wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pasiphae Group
The Pasiphae group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Pasiphae and are thought to have a common origin. Their semi-major axes (distances from Jupiter) range between 22.8 and 24.1 million km (the same range as the Carme group), their inclinations between 144.5° and 158.3°, and their eccentricities between 0.25 and 0.43. Core members of the group include (negative periods indicate retrograde orbits):Scott S. Sheppard, David C. Jewitt, Carolyn Porco ''Jupiter's outer satellites and Trojans'', In: ''Jupiter. The planet, satellites and magnetosphere.'' Edited by Fran Bagenal, Timothy E. Dowling, William B. McKinnon. Cambridge planetary science, Vol. 1, Cambridge, UK: Cambridge University Press, , 2004, p. 263 - 28Full text(pdf). The International Astronomical Union (IAU) reserves names ending in -e for all retrograde moons. Origin The Pasiphae group is believed to have been formed when Jupiter captured an asteroid which subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaare Aksnes
Kaare Aksnes (born 25 March 1938 in Kvam in Hardanger) is a professor at the Institute for Theoretical Astrophysics at the University of Oslo. Personal life He was born in Kvam, Hordaland as a brother of the chemist Gunnar Aksnes. His parents were farmers. In 1959 he married teacher Liv Kristin Marøy. Career He finished his secondary education in 1956, and graduated with the cand.real. degree in 1963, having studied in both Bergen and Oslo. From 1964 to 1965 he was a research assistant at Harestua. He then worked in the United States for several years, and took the Ph.D. at Yale University in 1969. His doctor's thesis is today a standard work within estimating the course of planets, moons, meteors, comets and artificial sounds. His work is among other things used by NASA's Voyager sounds to Jupiter, and he received the NASA Group Achievement Award for his work. After several years at the Center for Astrophysics Harvard & Smithsonian in Cambridge, Massachusetts he returned fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secular Resonance
A secular resonance is a type of orbital resonance between two bodies with synchronized precessional frequencies. In celestial mechanics, secular refers to the long-term motion of a system, and resonance is periods or frequencies being a simple numerical ratio of small integers. Typically, the synchronized precessions in secular resonances are between the rates of change of the argument of the periapses or the rates of change of the longitude of the ascending nodes of two system bodies. Secular resonances can be used to study the long-term orbital evolution of asteroids and their families within the asteroid belt. Description Secular resonances occur when the precession of two orbits is synchronised (a precession of the perihelion, with frequency g, or the ascending node, with frequency s, or both). A small body (such as a small Solar System body) in secular resonance with a much larger one (such as a planet) will precess at the same rate as the large body. Over relatively shor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ananke Group
The Ananke group is a group of retrograde irregular satellites of Jupiter that follow similar orbits to Ananke and are thought to have a common origin. Their semi-major axes (distances from Jupiter) range between 19.3 and 22.7 Gm, their orbital inclinations between 145.7° and 154.8°, and their orbital eccentricities between 0.02 and 0.28. The core members include (negative period indicates retrograde orbit): Scott S. Sheppard, David C. Jewitt, Carolyn Porco ''Jupiter's outer satellites and Trojans'', In: ''Jupiter. The planet, satellites and magnetosphere.'' Edited by Fran Bagenal, Timothy E. Dowling, William B. McKinnon. Cambridge planetary science, Vol. 1, Cambridge, UK: Cambridge University Press, , 2004, p. 263 - 28Full text(pdf). David Nesvorný, Cristian Beaugé, and Luke Dones ''Collisional Origin of Families of Irregular Satellites'', The Astronomical Journal, 127 (2004), pp. 1768–178Full text./ref> The International Astronomical Union (IAU) reserves names end ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for the diameter of a sphere. In more modern usage, the length d of a diameter is also called the diameter. In this sense one speaks of diameter rather than diameter (which refers to the line segment itself), because all diameters of a circle or sphere have the same length, this being twice the radius r. :d = 2r \qquad\text\qquad r = \frac. For a convex shape in the plane, the diameter is defined to be the largest distance that can be formed between two opposite parallel lines tangent to its boundary, and the is often defined to be the smallest such distance. Both quantities can be calculated efficiently using rotating calipers. For a curve of constant width such as the Reuleaux triangle, the width and diameter are the same because all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and silicaceous compositions, respectively. The size of asteroids varies greatly; the largest, Ceres, is almost across and qualifies as a dwarf planet. The total mass of all the asteroids combined is only 3% that of Earth's Moon. The majority of main belt asteroids follow slightly elliptical, stable orbits, revolving in the same direction as the Earth and taking from three to six years to comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded in 1919 and is based in Paris, France. The IAU is composed of individual members, who include both professional astronomers and junior scientists, and national members, such as professional associations, national societies, or academic institutions. Individual members are organised into divisions, committees, and working groups centered on particular subdisciplines, subjects, or initiatives. As of 2018, the Union had over 13,700 individual members, spanning 90 countries, and 82 national members. Among the key activities of the IAU is serving as a forum for scientific conferences. It sponsors nine annual symposia and holds a triannual General Assembly that sets policy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
