Photos courtesy A. Stern (SwRI), M. Buie (Lowell Observatory),
These maps, showing opposite hemispheres of Pluto, are based on Hubble
Space Telescope observations from 1996. Even Hubble's keen eyesight
just barely resolves Pluto, revealing some of the light and dark
patches on its surface.
Pluto is a challenging telescope target because it is so tiny
and so far away. It is only two-thirds the size of Earth's Moon,
but 1,200 times farther away. These observations were made when Pluto
was 3 billion miles from Earth.