Using the SPHERE receiver of the European Southern Observatory (ESO) Very Southern Telescope (VLT), astronomers noticed that the asteroid Hygea, the fourth largest body in the main asteroid belt, had a spherical shape and could potentially take away from Ceres the “title” of the smallest dwarf planet in the Solar System. Reports of scientific observations and conclusions are published in Nature Astronomy Journal.
“Thanks to the SPHERE receiver’s unique capabilities, one of the world’s most powerful imaging instruments, We were able to determine directly the form of the Hygea, which turned out to be roughly spherical, so that it could be reclassified into the dwarf planet, the smallest known to date, “says Pierre Vernazza, lead author of the Marseille (France) Astrophysical Laboratory report.
The origin of Gigay’s largest asteroid belt, discovered by Italian astronomer Annibale de Gasparis on April 12, 1849, meets three of the four criteria for dwarf planets at first glance: it revolves around the Sun, is not a satellite, and, unlike eight major planets, its orbit is not cleared.
The SPHERE tool also made it possible to refine the size of Gigeya and showed that its diameter is slightly more than 430 kilometers. Pluto, the most famous dwarf planet, has a diameter of about 2400 kilometers, and Ceres – about 950 kilometers.
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