page_title: 4 Vesta
section_title: Surface features
hierarchical_section_title: 4 Vesta / Surface features
caption_attribution_description: The asteroid (4) Vesta and the dwarf planet (1) Ceres shown alongside the Earth's Moon. The scale is 20 km/px. The image was made from File:Ceres optimized.jpg, [1], and Image:Moon PIA00302.jpg
context_page_description: 4 Vesta is the second most massive asteroid in the solar system, with an average diameter of about 530 km and an estimated mass 9% the mass of the entire asteroid belt. Its size and unusually bright surface makes Vesta the brightest asteroid, and the only one ever visible to the naked eye from Earth. Vesta's astronomical symbol is.
context_section_description: Some Vestian surface features have been resolved using the Hubble Space Telescope and ground based telescopes, e.g. the Keck Telescope.
  The most notable surface feature is a very large crater that is 460 km in diameter centered near the south pole. Its width is about 80% of the entire diameter of Vesta. The floor of this crater is about 13 km below, and its rim rises 4–12 km above the surrounding area, with total surface relief of about 25 km. A central peak rises 18 km above the crater floor. It is thought that the impact responsible blew up about 1% of the entire volume of Vesta, and it is likely that a group of smaller asteroids known as the Vesta family are the remains of this collision. If this is the case, then the fact that 10 km fragments of the Vesta family have survived bombardment until the present indicates that the crater is only about 1 billion years old or younger. It would also be the original site of origin of the HED meteorites. In fact, all the known V-type asteroids taken together account for only about 6% of the ejected volume, with the rest presumably either in small fragments, ejected by approaching the 3:1 Kirkwood gap, or perturbed away by radiation pressure. Spectroscopic analyses of the Hubble images have shown that this crater has penetrated deep through several distinct layers of the crust, and possibly into the mantle which is indicated by spectral signatures of olivine. Interestingly Vesta was not disrupted nor resurfaced by an impact of this magnitude.
  Several other large craters about 150 km wide and 7 km deep are also present. A dark feature about 200 km across has been named Olbers in honour of Vesta's discoverer, but it does not appear in elevation maps as a fresh crater would, and its nature is presently unknown, perhaps an old basaltic surface. It serves as a reference point with the 0° longitude prime meridian defined to pass through its center.
  The eastern and western hemispheres show markedly different terrains. From preliminary spectral analyses of the Hubble Space Telescope images, the eastern hemisphere appears to be have a highly reflective, heavily cratered "highland" terrain with old, dusty rocks, and craters probing into deeper plutonic layers of the crust. On the other hand, large regions of the western hemisphere are taken up by dark geologic units thought to be surface basalts.
caption: 4 Vesta and 1 Ceres alongside Earth's Moon.
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