Astronomers recently discovered that the dwarf planet 2007 OR10 – nicknamed ‘Snow White’ – is an icy world, with about half its surface covered in ice.
The new findings also suggested that the red-tinged dwarf planet might be covered in a thin layer of methane, the remnants of an atmosphere that’s slowly being lost into space.
“You get to see this nice picture of what once was an active little world with water volcanoes and an atmosphere, and it’s now just frozen, dead, with an atmosphere that’s slowly slipping away,” said Mike Brown, the Richard and Barbara Rosenberg Professor and professor of planetary astronomy, who is the lead author on a paper.
‘Snow White’ – which was discovered in 2007 as part of the PhD thesis of Brown’s former graduate student Meg Schwamb – orbits the Sun at the edge of the solar system and is about half the size of Pluto, making it the fifth largest dwarf planet.
At the time, Brown had guessed incorrectly that it was an icy body that had broken off from another dwarf planet named Haumea; he nicknamed it ‘Snow White’ for its presumed white colour.
As expected, ‘Snow White’ was red. But to their surprise, the spectrum revealed that the surface was covered in water ice.
There is, however, one other dwarf planet that’s both red and covered with water ice: Quaoar, which Brown helped discover in 2002.
The spectrum of 2007 OR10 looks similar to Quaoar’s, suggesting that what happened on Quaoar also happened on 2007 OR10.
“That combination — red and water — says to me, ‘methane,’” said Brown.
“We’re basically looking at the last gasp of Snow White. For four and a half billion years, Snow White has been sitting out there, slowly losing its atmosphere, and now there’s just a little bit left,” added Brown.
The study will be detailed in the Astrophysical Journal Letters.