Pluto’s heavy ‘heart’ may have led to ‘depression’

Ever since Nasa’s New Horizons spacecraft sent back the first high-resolution images of Pluto’s great white heart, scientists have been puzzling over its origin.

Some have suggested the planet rolled over to ensure this particular feature wound up in this particular spot; others say its location could indicate a subsurface ocean.

Now, a new study published on Wednesday in the journal Nature suggests that the bright western lobe of Pluto’s heart-shaped basin is akin to an ice cap that formed on the coldest part of the dwarf planet, much like the ice caps that have formed on Earth’s poles.

“We’re used to thinking that planets have two ice caps on each of the poles, but Pluto only has one ice cap as far as we know,” said Douglas Hamilton, an astronomy professor at the University of Maryland who led the work.

Unofficially known as Sputnik Planitia, the western lobe of Pluto’s “heart” is located in a depression about 600 miles wide and covered in nitrogen ice that is 2.5 miles thick. It’s distinctive for being smoother and brighter than the rest of the surface.