Large asteroid could be dwarf planet, says study

A giant rock thought to be the fourth largest asteroid in the solar system could be a dwarf planet, astronomers have said.

If reclassified, it would make Hygiea, located in the asteroid belt between Mars and Jupiter, the smallest dwarf planet in the solar system.

Measuring at just over 280 miles in diameter, astronomers say this celestial body could potentially take the crown from the 590-mile wide Ceres – also located in the rocky belt.

The findings, published in the journal Nature Astronomy, come after an international team of astronomers observed Hygiea using the European Southern Observatory’s Very Large Telescope (VLT).

A dwarf planet, according to the International Astronomical Union (IAU), is a celestial object orbiting a star that is massive enough to be rounded by its own gravity but does not have the gravitational dominance to clear the area around its orbit by consuming or slinging away smaller objects in its path.

The most famous example includes Pluto, which was downgraded to a dwarf planet in 2006 after the IAU changed the requirements that defined a planet.

Along with Ceres and Pluto, there are three other known dwarf planets in the solar system – Haumea, Makemake and Eris.

Ceres and Hygiea hail from the asteroid belt, sharing the vast space with 7,000 other members, including a large asteroid called Vesta.

To investigate how Hygiea got its spherical shape, the researchers peered through the VLT and analysed the data gathered using the telescope’s SPHERE instrument.

While high-resolution images showed Hygiea was rounded by its own gravity, the astronomers say they were “surprised” it lacked large impact craters, ie evidence of a major collision.

Study author Pierre Vernazza, from the Laboratoire d’Astrophysique de Marseille in France, said: “Thanks to these images, Hygiea may be reclassified as a dwarf planet.”