Archive for November 5, 2019

11/05/2019 – Ephemeris – Is the asteroid Hygiea the smallest dwarf planet?

November 5, 2019 Comments off

Ephemeris for Election Day in some places, Tuesday, November 5th. Today the Sun will be up for 10 hours even, setting at 5:26, and it will rise tomorrow at 7:27. The Moon, 1 day past first quarter, will set at 1:12 tomorrow morning.

The asteroid Hygiea is the 4th largest asteroid in the asteroid belt between Mars and Jupiter. After much study with the European Southern Observatory’s Very Large Telescope (VLT) it appears that Hygiea is very nearly spherical. Only the largest asteroid and dwarf planet Ceres is more spherical, and it’s over twice as large. Ceres is 587 miles (945 km) in diameter. Hygiea is 267 miles (430 km) in diameter. By current definition that a body not fitting the definition of planet because it hadn’t cleared it’d orbit of other objects could have the classification of dwarf planet of it was round, or in astronomer-speak has achieved hydrostatic equilibrium. If the International Astronomical Union agrees it would be the smallest dwarf planet.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


SPHERE image of Hygiea

A new SPHERE/VLT image of Hygiea, which could be the Solar System’s smallest dwarf planet yet. 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 have enough mass that its own gravity pulls it into a roughly spherical shape. This is what VLT observations have now revealed about Hygiea.

For more from Universe Today: