pluto

Pluto, long thought of as a dormant chunk of ice and rock, has recently undergone some of the most dramatic surface changes of any body in the solar system. And Marc Buie has the images to prove it. When Buie, a planetary scientist at the Southwest Research Institute in Boulder, Colo., completed a lengthy analysis of pictures of Pluto taken by the Hubble Space Telescope in 2002 and 2003, he couldn’t believe his eyes. Sometime in the two years before those images were taken, the dwarf planet had inexplicably gotten significantly redder. The abrupt color change “has gotten me scared for a while,” Buie told reporters during a telephone press briefing on February 4. An increase in the amount of ultraviolet sunlight breaking down methane on Pluto’s surface could account for the redder hue. But Pluto’s position relative to the sun didn’t change enough during that two-year period to provide such higher UV levels. “That’s what makes it so surprising,” Buie noted.