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2 Pallas
Pallas ( minor-planet designation: 2 Pallas) is the second asteroid to have been discovered, after Ceres. It is believed to have a mineral composition similar to carbonaceous chondrite meteorites, like Ceres, though significantly less hydrated than Ceres. It is the third-largest asteroid in the Solar System by both volume and mass, and is a likely remnant protoplanet. It is 79% the mass of Vesta and 22% the mass of Ceres, constituting an estimated 7% of the mass of the asteroid belt. Its estimated volume is equivalent to a sphere in diameter, 90–95% the volume of Vesta. During the planetary formation era of the Solar System, objects grew in size through an accretion process to approximately the size of Pallas. Most of these protoplanets were incorporated into the growth of larger bodies, which became the planets, whereas others were ejected by the planets or destroyed in collisions with each other. Pallas, Vesta and Ceres appear to be the only intact bodies from t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pallas Symbol (bold)
Pallas may refer to: Astronomy * 2 Pallas asteroid ** Pallas family, a group of asteroids that includes 2 Pallas * Pallas (crater), a crater on Earth's moon Mythology * Pallas (Giant), a son of Uranus and Gaia, killed and flayed by Athena * Pallas (son of Evander), a prominent character in the ''Aeneid'' * Pallas (son of Lycaon), a teacher of Athena * Pallas (son of Pandion), the father of the 50 Pallantides * Pallas (Titan), the son of Crius and Eurybia, brother of Astraeus and Perses, and husband of Styx * Pallas (daughter of Triton) * Pallas, an epithet of Athena * Pallas, the father of Euryalus by Diomede People * Pallas (freedman) or Marcus Antonius Pallas, a freedman and favorite of Emperor Claudius * Pallas, a secondary wife of Herod the Great; her origins and fate are unknown. People with the surname * David Pallas (born 1980), Swiss footballer * Janette Pallas * José Ignacio Pallas (born 1983), Uruguayan football defender * Maria Pallas (born 1993), Estonian swimme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar System" and "solar system" structures in theinaming guidelines document. The name is commonly rendered in lower case ('solar system'), as, for example, in the ''Oxford English Dictionary'' an''Merriam-Webster's 11th Collegiate Dictionary''. is the gravity, gravitationally bound system of the Sun and the objects that orbit it. It Formation and evolution of the Solar System, formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The solar mass, vast majority (99.86%) of the system's mass is in the Sun, with most of the Jupiter mass, remaining mass contained in the planet Jupiter. The four inner Solar System, inner system planets—Mercury (planet), Mercury, Venus, Earth and Mars—are terrest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon And Asteroids 1 To 10
The Moon is Earth's only natural satellite. It is the List of natural satellites, fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia (continent), Australia). The Moon is a planetary-mass object with a planetary differentiation, differentiated Terrestrial planet, rocky body, making it a satellite planet under the geophysical definition of planet, geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant Atmosphere of the Moon, atmosphere, hydrosphere, or Magnetic field of the Moon, magnetic field. Its surface gravity is about one-sixth of Earth's at , with Jupiter's moon Io (moon), Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an lunar distance (astronomy), average distance of , or about 30 tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sirius
Sirius is the list of brightest stars, brightest star in the night sky. Its name is derived from the Ancient Greek language, Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinisation of names, Latinized to Alpha Canis Majoris, and abbreviated Alpha CMa or α CMa. With a visual apparent magnitude of −1.46, Sirius is almost twice as bright as Canopus, the next brightest star. Sirius is a binary star consisting of a main-sequence star of spectral type A-type main-sequence star, A0 or A1, termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. The distance between the two varies between 8.2 and 31.5 astronomical units as they orbit every 50 years. Sirius appears bright because of its intrinsic luminosity and its proximity to the Solar System. At a distance of , the Sirius system is one of Earth's List of nearest stars, nearest neighbours. Sirius is gradually moving closer to the Solar S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume, by a small margin, but is slightly less massive than Eris (dwarf planet), Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Compared to Moon, Earth's moon, Pluto has only one sixth its mass and one third its volume. Pluto has a moderately orbital eccentricity, eccentric and inclined orbit, ranging from from the Sun. Light from the Sun takes 5.5 hours to reach Pluto at its average distance (). Pluto's eccentric orbit periodically brings it closer to the Sun than Neptune, but a stable orbital resonance prevents them from colliding. Pluto has moons of Pluto, five known moons: Charon (moon), Charon, the larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Eccentricity
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the Galaxy. Definition In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit. The eccentricity of this Kepler orbit is a non-negative number that defines its shape. The eccentricity may take the following values: * circular orbit: ''e'' = 0 * elliptic orbit: 0 < ''e'' < 1 * [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetoid
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor planet'', but that year's meeting reclassified minor planets and comets into dwarf planets and small Solar System bodies (SSSBs).Press release, IAU 2006 General Assembly: Result of the IAU Resolution votes International Astronomical Union, August 24, 2006. Accessed May 5, 2008. Minor planets include asteroids ( |
Minor Planet
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor planet'', but that year's meeting reclassified minor planets and comets into dwarf planets and small Solar System bodies (SSSBs).Press release, IAU 2006 General Assembly: Result of the IAU Resolution votes International Astronomical Union, August 24, 2006. Accessed May 5, 2008. Minor planets include asteroids ( |
List Of Former Planets
This is a list of astronomical objects formerly widely considered ''planets'' under any of the various definitions of this word in the history of astronomy. As the definition of planet, definition of ''planet'' has evolved, the wikt:en:de facto#English, de facto and wikt:en:de jure#English, de jure definitions of wikt:en:planet#English, planet have changed over the millennia. As of 2022, there are IAU definition of planet, 8 official planets in the Solar System by the IAU, and many more exoplanets. Several objects formerly considered exoplanets have been found actually to be stars or brown dwarfs. Background Throughout antiquity, several astronomical objects were considered Classical Planets, meaning "wandering stars", not all of which are now considered planets. The natural satellite, moons discovered around Jupiter, Saturn and Uranus after the advent of the telescope were also initially considered planets by some. The development of more powerful telescopes resulted in the discov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinrich Wilhelm Matthäus Olbers
Heinrich Wilhelm Matthias Olbers (; ; 11 October 1758 – 2 March 1840) was a German physician and astronomer. Life and career Olbers was born in Arbergen, Germany, today part of Bremen, and studied to be a physician at Göttingen (1777–80). While he was at Göttingen, he studied mathematics with Abraham Gotthelf Kästner. In 1779, while attending to a sick fellow student, he devised a method of calculating cometary orbits which made an epoch in the treatment of the subject. It was the first satisfactory method of calculating cometary orbits. After his graduation in 1780, he began practicing medicine in Bremen. At night he dedicated his time to astronomical observation, making the upper story of his home into an observatory. In 1800, Olbers was one of 24 astronomers invited to participate in the group known as the "celestial police", dedicated to finding new planets in the solar system. On 28 March 1802, Olbers discovered and named the asteroid Pallas. Five years later, on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. The Solar System has at least eight planets: the terrestrial planets Mercury, Venus, Earth and Mars, and the giant planets Jupiter, Saturn, Uranus and Neptune. These planets each rotate around an axis tilted with respect to its orbital pole. All of them possess an atmosphere, although that of Mercury is tenuous, and some share such features as ice caps, seasons, volcanism, hurricanes, tectonics, and even hydrology. Apart from Venus and Mars, the Solar System planets generate magnetic fields, and all except Venus and Mercury have natural satellites. The giant planets bear plan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accretion (astrophysics)
In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, in an accretion disk. Most astronomical objects, such as galaxies, stars, and planets, are formed by accretion processes. Overview The accretion model that Earth and the other terrestrial planets formed from meteoric material was proposed in 1944 by Otto Schmidt, followed by the ''protoplanet theory'' of William McCrea (1960) and finally the ''capture theory'' of Michael Woolfson. For details of Kant's position, see In 1978, Andrew Prentice resurrected the initial Laplacian ideas about planet formation and developed the ''modern Laplacian theory''. None of these models proved completely successful, and many of the proposed theories were descriptive. The 1944 accretion model by Otto Schmidt was further developed in a quantitative way in 1969 by Viktor Safronov. He calculated, in detail, the different stages of terrestrial plane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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