Seeing Red

Pluto, which isn't a planet, is acting funny. Specifically, the remote dwarf planet is turning red. Marc Buie, a planetary scientist in Boulder, used Hubble Space Telescope images to study Pluto and noticed a distinct reddening of the non-planet's surface some time about the year 2000. Since Pluto wasn't kicked out of the planet club until 2006, it can't be blushing from embarassment, as some have suggested.

It's possible that some phenomenon is releasing reddish methane compounds, though exactly how that could happen on a world as cold as Pluto is unclear. Perhaps the New Horizons probe will reveal more about what's changing Pluto's color. We'll find out in five years.