Pluto's Changing Color

Images taken by the Hubble space telescope show the dwarf planet Pluto, on the edge of our solar system, is redder than it used to be.
From 1954 to 2000, Pluto didn't change in color when it was photographed from Earth. But after that, it did. The red levels increased by 20 percent, maybe up to 30 percent, and stabilized from about 2000 to 2002.
Nasa's scientists believe these are seasonal changes - as the planet heads into a new phase of its 248-year-long seasonal cycle.
The new images are said to show frozen nitrogen brightening in the north and becoming darker in the south.