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{{short description|Impact crater on the surface of the asteroid 4 Vesta}}{{about|the crater on 4 Vesta|Ilia, the mother of Romulus and Remus|Rhea Silvia}}{{Use dmy dates|date=September 2019}}

factoids

|coordinates_footnotes =List of tallest mountains in the Solar System>One of the tallest known mountains in the Solar System4 Vesta>Vesta 505abbr=on}}20-25mi ftLAST=VEGADATE=11 OCTOBER 2011PUBLISHER=NASAARCHIVE-DATE=17 OCTOBER 2013ACCESSDATE=17 FEBRUARY 2018, SCHENK>FIRST1=PAULTITLE=THE GEOLOGICALLY RECENT GIANT IMPACT BASINS AT VESTA'S SOUTH POLESCIENCE (JOURNAL)>SCIENCEVOLUME=336PAGES=694–697DOI=10.1126/SCIENCE.1223272S2CID=206541950, |discoverer = Hubble Space Telescope |eponym = Rhea Silvia, a mythological vestal virgin and mother of the founders of Rome, Romulus and Remus}}Rheasilvia {{IPAc-en|ˌ|r|i:|@|'|s|I|l|v|i|@}} is the largest impact crater on the asteroid Vesta. It is {{convert|505|km|mi|abbr=on}} in diameter, which is 90% the diameter of Vesta itself, and is 95% the mean diameter of Vesta, {{convert|529|km|mi|abbr=on}}. However, the mean is affected by the crater itself. It is 89% the mean equatorial diameter of {{convert|569|km|mi|abbr=on}}, 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 {{convert|200|km|mi|abbr=on}} in diameter, and rises {{convert|22.5|km|mi ft|abbr=on}} from its base,WEB,weblink New View of Vesta Mountain From NASA's Dawn Mission, Vega, Priscilla, 11 October 2011, dawn.jpl.nasa.gov, NASA,weblink" title="web.archive.org/web/20131017003603weblink">weblink 17 October 2013, dead, 17 February 2018, making it one of the tallest mountains known in the Solar System.

Discovery

Rheasilvia was discovered in Hubble Space Telescope images in 1997,WEB,weblink Hubble Reveals Huge Crater on the Surface of the Asteroid Vesta, 4 September 1997, HubbleSite, Space Telescope Science Institute, 4 July 2018, but was not named until the arrival of the Dawn spacecraft in 2011. It is named after Rhea Silvia, a mythological vestal virgin and mother of the founders of Rome, Romulus and Remus. The name Rheasilvia was officially approved by the International Astronomical Union (IAU) on 30 September 2011.{{GPN|14886|Rheasilvia}}(NASA coordinates)

Characteristics

The crater partially obscures an earlier crater, named Veneneia, that at {{convert|395|km|mi|abbr=on}} is almost as large.NEWS,weblink Vesta seems more planet than asteroid, Drake, Nadia, Nadia Drake, 22 March 2012, Science News, Rheasilvia has an escarpment along part of its perimeter which rises {{convert|4–12|km|mi|abbr=on}} above the surrounding terrain. The crater floor lies about {{convert|13|km|mi}} below the surrounding surface. This basin consists of undulating terrain and a central mound almost {{convert|200|km|mi|abbr=on}} in diameter, which rises {{convert|20-25|km|mi ft|abbr=on}} from its base,WEB,weblink New View of Vesta Mountain From NASA's Dawn Mission, Vega, Priscilla, 11 October 2011, dawn.jpl.nasa.gov, NASA,weblink" title="web.archive.org/web/20131017003603weblink">weblink 17 October 2013, dead, 17 February 2018, one of the tallest known mountains in the Solar System, and possibly formed due to a planetary scale impact.JOURNAL, Karimi, Saman, Dombard, Andrew J., 2016, On the possibility of viscoelastic deformation of the large south polar craters and true polar wander on the asteroid Vesta, Journal of Geophysical Research, 121, 9, 1786–1797, 2016JGRE..121.1786K, 10.1002/2016JE005064, free, Spectroscopic analyses of Hubble images have shown that this crater has penetrated deep through several distinct layers of the crust, and possibly into the mantle, as indicated by spectral signatures of olivine.JOURNAL, Thomas, Peter C., et al., July 1997, Vesta: Spin Pole, Size, and Shape from HST Images, Icarus (journal), Icarus, 128, 1, 88–94, 1997Icar..128...88T, 10.1006/icar.1997.5736, free, Vesta has a series of troughs in an equatorial region concentric to Rheasilvia. These are thought to be large-scale fractures resulting from the impact. The largest is Divalia Fossae, approx. {{convert|22|km|mi|abbr=on}} wide and {{convert|465|km|mi|abbr=on}} long.It is estimated that the impact responsible excavated about 1% of the volume of Vesta, and it is likely that the Vesta family and V-type asteroids are the products of this collision. If this is the case, then the fact that 10-km fragments have survived bombardment until the present indicates that the crater is at most about 1 billion years old.JOURNAL, Binzel, Richard P., et al., 1997, Geologic Mapping of Vesta from 1994 Hubble Space Telescope Images, Icarus (journal), Icarus, 128, 1, 95–103, 1997Icar..128...95B, 10.1006/icar.1997.5734, free, It would also be the origin of the HED meteorites. Known V-type asteroids account for 6% of the ejected volume, with the rest of the fragments presumably either too small to observe, or removed from the asteroid belt by approaching the 3:1 Kirkwood gap, by the Yarkovsky effect, or (in the case of small fragments) by radiation pressure.

Gallery {|

thumb|Elevation map of Vesta's southern hemisphere. Higher elevations (red) are found on the crater rim (occluding VeneneiaVeneneiathumb|Outlines of Rheasilvia and Veneneia, the latter being partially obliterated by the former.)thumbHubble Space Telescope>HubbleHubble Space Telescope>Hubble{|thumb|Computer-generated oblique view of Rheasilvia, with color-coded elevation in the lower version. A flyover video is available at the source.)thumb|Shaded-relief topographic map of Vesta's southern hemisphere, showing Rheasilvia and Veneneia.)thumbAnaglyph 3D>anaglyphAnaglyph 3D>anaglyph

See also

• List of largest craters in the Solar System
• List of tallest mountains in the Solar System
• Lists of astronomical objects

References

{{Reflist}}{{4 Vesta}}