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Planetary Embryo
A protoplanet is a large planetary embryo that originated within a protoplanetary disc and has undergone internal melting to produce a differentiated interior. Protoplanets are thought to form out of kilometer-sized planetesimals that gravitationally perturb each other's orbits and collide, gradually coalescing into the dominant planets. The planetesimal hypothesis A planetesimal is an object formed from dust, rock, and other materials, measuring from meters to hundreds of kilometers in size. According to the Chamberlin–Moulton planetesimal hypothesis and the theories of Viktor Safronov, a protoplanetary disk of materials such as gas and dust would orbit a star early in the formation of a planetary system. The action of gravity on such materials form larger and larger chunks until some reach the size of planetesimals. It is thought that the collisions of planetesimals created a few hundred larger planetary embryos. Over the course of hundreds of millions of years, they colli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vesta Full Mosaic
Vesta may refer to: Fiction and mythology * Vesta (mythology), Roman goddess of the hearth and home * Vesta (Marvel Comics), a Marvel Comics character * Sailor Vesta, a character in ''Sailor Moon'' Brands and products * Lada Vesta, a car from Russian car manufacturer AVTOVAZ * Swan Vesta (began 1883), a brand of matches ** Vesta case, metal containers for matches (which were previously called vestas) * Vesta, a freeze-dried meal brand launched in the United Kingdom by Batchelors in the early 1970s, and now owned by Premier Foods. Music * Vesta (1957–2011), stage name of American recording artist Vesta Williams ** ''Vesta'' (album), 1986 album by Vesta Williams ** '' Vesta 4 U'', 1988 album by Vesta Williams * Vesta, a 2008 rock band made up of former members of The Juliana Theory Places * Monte Vesta, Lombardy, Italy * Temple of Vesta, Rome, Italy * Vesta Nunataks, Alexander Island, Antarctica * 4 Vesta, an asteroid Canada * Vesta Creek (Alberta), a stream in northern A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Impact Hypothesis
The giant-impact hypothesis, sometimes called the Big Splash, or the Theia Impact, suggests that the Moon formed from the ejecta of a collision between the proto-Earth and a Mars-sized planet, approximately 4.5 billion years ago, in the Hadean eon (about 20 to 100 million years after the Solar System coalesced). The colliding body is sometimes called Theia, from the name of the mythical Greek Titan who was the mother of Selene, the goddess of the Moon. Analysis of lunar rocks, published in a 2016 report, suggests that the impact might have been a direct hit, causing a thorough mixing of both parent bodies. The giant-impact hypothesis is currently the favored scientific hypothesis for the formation of the Moon. Supporting evidence includes: * Earth's spin and the Moon's orbit have similar orientations. * The Earth–Moon system contains an anomalously high angular momentum. Meaning, the momentum contained in Earth's rotation, the Moon's rotation, and the Moon revolving aro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MSNBC
MSNBC (originally the Microsoft National Broadcasting Company) is an American news-based pay television cable channel. It is owned by NBCUniversala subsidiary of Comcast. Headquartered in New York City, it provides news coverage and political commentary. As of September 2018, approximately 87 million households in the United States (90.7 percent of pay television subscribers) were receiving MSNBC. In 2019, MSNBC ranked second among basic cable networks averaging 1.8 million viewers, behind rival Fox News, averaging 2.5 million viewers. MSNBC and its website were founded in 1996 under a partnership between Microsoft and General Electric's NBC unit, hence the network's naming. Microsoft divested itself of its stakes in the MSNBC channel in 2005 and its stakes in msnbc.com in July 2012. The general news site was rebranded as NBCNews.com, and a new msnbc.com was created as the online home of the cable channel. In the late summer of 2015, MSNBC revamped its programming by ente ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dwarf Planet
A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to planetary geologists is that they may be geologically active bodies, an expectation that was borne out in 2015 by the '' Dawn'' mission to and the '' New Horizons'' mission to Pluto. Astronomers are in general agreement that at least the nine largest candidates are dwarf planets: Pluto, , , , , , , , and . Of these and the tenth-largest candidate , all but Sedna have either been visited by spacecraft (Pluto and Ceres) or have at least one known moon (Pluto, Eris, Haumea, Makemake, Gonggong, Quaoar, Orcus, and Salacia), which allows their masses and thus an estimate of their densities to be determined. Mass and density in turn can be fit into geophysical models in an attempt to determine the nature of these worlds. Some astronomers includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kuiper Belt
The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times as wide and 20–200 times as massive. Like the asteroid belt, it consists mainly of small bodies or remnants from when the Solar System formed. While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia, and water. The Kuiper belt is home to most of the objects that astronomers generally accept as dwarf planets: Orcus, Pluto, Haumea, Quaoar, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, may have originated in the region. The Kuiper belt was named after Dutch astronomer Gerard Kuiper, although he did not predict its existence. In 1992, minor planet (15760 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discovery News
Discovery, Inc. was an American multinational mass media factual television conglomerate based in New York City. Established in 1985, the company operated a group of factual and lifestyle television brands, such as the namesake Discovery Channel, Animal Planet, Science Channel, and TLC. In 2018, the company acquired Scripps Networks Interactive, adding networks such as Food Network, HGTV, and Travel Channel to its portfolio. Since the purchase, Discovery described itself as serving members of "passionate" audiences, and also placed a larger focus on streaming services built around its properties. Discovery owned or had interests in local versions of its channel brands in international markets, in addition to its other major regional operations such as Eurosport (a pan-European group of sports channels, most prominently the rightsholder of the Olympic Games throughout most of Europe), GolfTV (an international golf-focused streaming service, which is the international digital rig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discovery Communications
Discovery, Inc. was an American multinational mass media factual television conglomerate based in New York City. Established in 1985, the company operated a group of factual and lifestyle television brands, such as the namesake Discovery Channel, Animal Planet, Science Channel, and TLC. In 2018, the company acquired Scripps Networks Interactive, adding networks such as Food Network, HGTV, and Travel Channel to its portfolio. Since the purchase, Discovery described itself as serving members of "passionate" audiences, and also placed a larger focus on streaming services built around its properties. Discovery owned or had interests in local versions of its channel brands in international markets, in addition to its other major regional operations such as Eurosport (a pan-European group of sports channels, most prominently the rightsholder of the Olympic Games throughout most of Europe), GolfTV (an international golf-focused streaming service, which is the international digital r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
21 Lutetia
) , mp_category= Main belt , mpc_name=(21) Lutetia , orbit_ref = , epoch=May 31, 2020 ( JD 2459000.5) , semimajor=2.435 AU , perihelion=2.037 AU , aphelion=2.833 AU , eccentricity=0.16339 , period=3.80 yr (1388.1 d) , inclination=3.064° , asc_node=80.867° , arg_peri=249.997° , mean_anomaly=87.976° , dimensions=c/a = P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. ''Astronomy & Astrophysics'' 54, A56 , mean_radius = , volume= , mass= , density= , rotation=0.3402 d (8.1655 h) , axial_tilt = 96° , right_asc_north_pole = 51.8 ± 0.4° , declination = +10.8 ± 0.4° , spectral_type= M (Tholen) , magnitude = 9.25 to 13.17 , abs_magnitude=7.29 , albedo=0.19 ± 0.01 (geometrical)0.073 ± 0.002 (bond) , single_temperature=170–245 K Lutetia (minor planet designation: 21 Lutetia) is a large M-type asteroid in the main asteroid belt. It measures about 100 kilometers in diameter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
9 Metis
Metis ( minor planet designation: 9 Metis) is one of the larger main-belt asteroids. It is composed of silicates and metallic nickel-iron, and may be the core remnant of a large asteroid that was destroyed by an ancient collision. Metis is estimated to contain just under half a percent of the total mass of the asteroid belt. Metis passed within 0.034AU, or , of Vesta on 19 August 2004. Discovery and naming Metis was discovered by Andrew Graham on 25 April 1848, at Markree Observatory in Ireland; it was his only asteroid discovery. It also has been the only asteroid to have been discovered as a result of observations from Ireland until 7 October 2008, when, 160 years later, Dave McDonald from observatory J65 discovered (281507) 2008 TM9. Its name comes from the mythological Metis, a Titaness and Oceanid, daughter of Tethys and Oceanus. The name ''Thetis'' was also considered and rejected (it would later devolve to 17 Thetis). Characteristics Lightcurve-based 3D-mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
16 Psyche
16 Psyche () is a large M-type asteroid discovered by the Italian astronomer Annibale de Gasparis on 17 March 1852 and named after the Greek goddess Psyche. The prefix "16" signifies that it was the sixteenth minor planet in order of discovery. It is the largest and most massive of the M-type asteroids, and one of the dozen most massive asteroids. It has a mean diameter of approximately and contains about one percent of the mass of the asteroid belt. Historically, it was hypothesized to be the exposed core of a protoplanet, but numerous recent studies have all but ruled that out. Psyche will be explored by the spacecraft of the same name, with launch planned in 2023 and arrival in 2029. Symbol Astronomers created icon-like symbols for the first fifteen asteroids to be discovered, as a type of shorthand notation consistent with older notation for the classical planets. Psyche was given an iconic symbol, as were a few other asteroids discovered after 16 Psych ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4 Vesta
Vesta ( minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, the virgin goddess of home and hearth from Roman mythology. Vesta is thought to be the second-largest asteroid, both by mass and by volume, after the dwarf planet Ceres, though in volume it overlaps with the uncertainty in the measurements of 2 Pallas.Marsset, M., Brož, M., Vernazza, P. et al. The violent collisional history of aqueously evolved (2) Pallas. Nat Astron 4, 569–576 (2020). https://doi.org/10.1038/s41550-019-1007-5 Measurements give it a nominal volume only slightly larger than that of Pallas (about 5% greater, which is the magnitude of the uncertainties in measurement), but it is 25% to 30% more massive. It constitutes an estimated 9% of the mass of the asteroid belt. Vesta is the only known remaining rocky protoplanet ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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