Vesta is one of the largest objects in the asteroid belt, with a mean diameter of 525 kilometres (326 mi). 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.
Dawn is a retired space probe that was launched by NASA in September 2007 with the mission of studying two of the three known protoplanets of the asteroid belt: Vesta and Ceres. In the fulfillment of that mission—the ninth in NASA's Discovery Program—Dawn entered orbit around Vesta on July 16, 2011, and completed a 14-month survey mission before leaving for Ceres in late 2012. It entered orbit around Ceres on March 6, 2015. In 2017, NASA announced that the planned nine-year mission would be extended until the probe's hydrazine fuel supply was depleted. On November 1, 2018, NASA announced that Dawn had depleted its hydrazine, and the mission was ended. The derelict probe remains in a stable orbit around Ceres.
2867 Šteins is an irregular, diamond-shaped background asteroid from the inner regions of the asteroid belt, approximately 5 kilometers in diameter. It was discovered on 4 November 1969 by Soviet astronomer Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnij on the Crimean peninsula. In September 2008, ESA's spacecraft Rosetta flew by Šteins, making it one of few minor planets ever visited by a spacecraft. The bright E-type asteroid features 23 named craters and has a rotation period of 6.05 hours. It was named for Soviet Latvian astronomer Kārlis Šteins.
Davies is a crater on Mars located at 46°N 0°E on the fringe of Acidalia Planitia near Arabia Terra. It is approximately 48 km in diameter. The crater's name was formally approved by the IAU in 2006.
HED meteorites are a clan (subgroup) of achondrite meteorites. HED stands for "howardite–eucrite–diogenite". These achondrites came from a differentiated parent body and experienced extensive igneous processing not much different from the magmatic rocks found on Earth and for this reason they closely resemble terrestrial igneous rocks.
Ceres is a dwarf planet in the middle main asteroid belt between the orbits of Mars and Jupiter. It was the first known asteroid, discovered on 1 January 1801 by Giuseppe Piazzi at Palermo Astronomical Observatory in Sicily, and announced as a new planet. Ceres was later classified as an asteroid and then a dwarf planet, the only one inside Neptune's orbit.
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be gravitationally rounded, but insufficient to achieve orbital dominance like the eight classical planets of the Solar System. The prototypical dwarf planet is Pluto, which for decades was regarded as a planet before the "dwarf" concept was adopted in 2006.
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). In contrast to the eight official planets of the Solar System, all minor planets fail to clear their orbital neighborhood.
Rheasilvia is the largest impact crater on the asteroid Vesta. It is 505 km (314 mi) in diameter, which is 90% the diameter of Vesta itself, and is 95% the mean diameter of Vesta, 529 km (329 mi). However, the mean is affected by the crater itself. It is 89% the mean equatorial diameter of 569 km (354 mi), making it one of the largest craters in the Solar System, and at 75°S latitude, covers most of the southern hemisphere. The peak in the center of the crater is 200 km (120 mi) in diameter, and rises 22.5 km from its base, making it one of the tallest mountains known in the Solar System.
Tarpeia is an impact crater on the asteroid 4 Vesta. It is named after the Roman Vestal Virgin Tarpeia, who, according to legend, betrayed the city of Rome to the Sabines. The name Tarpeia was officially approved by the International Astronomical Union (IAU) on 27 December 2011.
Divalia Fossae is the largest of the series of parallel equatorial troughs on the giant asteroid 4 Vesta. It is one of the longest chasms in the Solar System, stretching across roughly two-thirds of Vesta's equator. The trough system is named after the Roman festival of Divalia; the name Divalia Fossae was officially approved by the International Astronomical Union (IAU) on 27 December 2011.
Saturnalia Fossae is a series of parallel Veneneian troughs in the northern hemisphere of the giant asteroid 4 Vesta. It is thought to be a shock fractures resulting from the impact that created Veneneia crater, which it is concentric with. It is one of the longer chasms in the Solar System.
Feralia Planitia is the third-largest known impact structure on the asteroid Vesta, after Rheasilvia and Veneneia. It is one of several old, degraded impact basins that predate the Rheasilvia basin that now dominates Vesta. It is situated near the equator, and is 270 kilometres (170 mi) across east to west, though compressed latitudinally by the Rheasilvia impact.
Occator is an impact crater located on Ceres, the largest object in the main asteroid belt that lies between the orbits of Mars and Jupiter, that contains "Spot 5", the brightest of the bright spots observed by the Dawn spacecraft. It was known as "Region A" in ground-based images taken by the W. M. Keck Observatory on Mauna Kea.
The geology of Ceres consists of the characteristics of the surface, the crust and the interior of the dwarf planet Ceres. The surface of Ceres is comparable to the surfaces of Saturn's moons Rhea and Tethys, and Uranus's moons Umbriel and Oberon.
PateraPAT-ər-ə is an irregular crater, or a complex crater with scalloped edges on a celestial body. Paterae can have any origin, although the majority of them were created by volcanism. The term comes from Latin, where it refers to a shallow bowl used in antique cultures.
Selk is a crater on Titan, a moon of Saturn, located at 7°N 199°W. It is a geologically young impact crater that measures approximately 90 kilometres (56 mi) in diameter.
Pola Regio is a geological structure on the asteroid 243 Ida. It was named after Pula (Pola), the place where Austrian astronomer Johann Palisa discovered Ida on 29 September 1884; this name was officially approved by the International Astronomical Union (IAU) in 1997. It is located on Ida's 180° E end, antipodal to Vienna Regio.
Vestalia Terra is a large highland plateau on the giant asteroid Vesta. Situated in Vesta's eastern hemisphere, Vestalia Terra is located near the equator and hosts the tallest point on Vesta. One of the largest named features on Vesta, it contains some of the most ancient terrain known on the asteroid. Additionally, Vestalia Terra is one of the few remaining magmatic features discovered on Vesta.
