What was thought to be an asteroid known as Hygiea was believed the be the fourth largest object in the asteroid belt, situated between Mars and Jupiter, behind asteroids Vesta, Pallas and dwarf planet Ceres. However, new research conducted by using the European Southern Observatory (ESO) has found that Hygiea could be a dwarf planet too – making it the smallest of its kind in our solar system with a diameter of just 430km, considerably less than the 556km between London and Glasgow. Ceres has a diameter of 950km, while Pluto, the most controversial of the dwarf planets as it was only downgraded from a planet in 2006, has a diameter of 1,200km.
To qualify as a dwarf planet, an object needs to have three of four requirements.
It needs to have enough of a gravitational pull to form itself into a sphere, it needs to orbit the Sun, it is not a moon and it does not need to clear a path through other debris such as asteroids, which is what regular planets do.
Using the Very Large Telescope (VLT), a planet-hunting telescope used by the ESO, and its SPHERE instrument, which helps to gauge the brightness of an object, experts believe that Hygiea could be a dwarf planet.
Lead researcher Pierre Vernazza from the Laboratoire d’Astrophysique de Marseille in France said: “Thanks to the unique capability of the SPHERE instrument on the VLT, which is one of the most powerful imaging systems in the world, we could resolve Hygiea’s shape, which turns out to be nearly spherical.
“Thanks to these images, Hygiea may be reclassified as a dwarf planet, so far the smallest in the Solar System.
“Thanks to the VLT and the new generation adaptive-optics instrument SPHERE, we are now imaging main belt asteroids with unprecedented resolution, closing the gap between Earth-based and interplanetary mission observations.”
Scientists had believes Hygiea would have a large impact crater, which was theorised from distant observations.
READ MORE: Ice Age shock: ‘Extraterrestrial’ object may have sparked extinction
The researchers observed 95 percent of Hygiea’s surface and could only see two unambiguous craters.
Study co-author Miroslav Bro of the Astronomical Institute of Charles University in Prague, Czech Republic, added: “Neither of these two craters could have been caused by the impact that originated the Hygiea family of asteroids whose volume is comparable to that of a 100 km-sized object. They are too small.”
