ESO: Smallest Dwarf Planet Yet in the Solar System?
Posted: Mon Oct 28, 2019 5:09 pm
ESO Telescope Reveals What Could be the
Smallest Dwarf Planet Yet in the Solar System
ESO Science Release | VLT | SPHERE | 2019 Oct 28
A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea ~ P. Vernazza et al
Smallest Dwarf Planet Yet in the Solar System
ESO Science Release | VLT | SPHERE | 2019 Oct 28
Astronomers using ESO’s SPHERE instrument at the Very Large Telescope (VLT) have revealed that the asteroid Hygiea could be classified as a dwarf planet. The object is the fourth largest in the asteroid belt after Ceres, Vesta and Pallas. For the first time, astronomers have observed Hygiea in sufficiently high resolution to study its surface and determine its shape and size. They found that Hygiea is spherical, potentially taking the crown from Ceres as the smallest dwarf planet in the Solar System.
As an object in the main asteroid belt, Hygiea satisfies right away three of the four requirements to be classified as a dwarf planet: it orbits around the Sun, it is not a moon and, unlike a planet, it has not cleared the neighbourhood around its orbit. The final requirement is that it has enough mass for its own gravity to pull it into a roughly spherical shape. This is what VLT observations have now revealed about Hygiea. ...
The team also used the SPHERE observations to constrain Hygiea’s size, putting its diameter at just over 430 km. Pluto, the most famous of dwarf planets, has a diameter close to 2400 km, while Ceres is close to 950 km in size.
Surprisingly, the observations also revealed that Hygiea lacks the very large impact crater that scientists expected to see on its surface ...
A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea ~ P. Vernazza et al
- Nature Astronomy (online 28 Oct 2019) DOI: 10.1038/s41550-019-0915-8 (pdf)