Hubble details Pluto's mottled coloring

WASHINGTON, Feb. 4 (UPI) -- NASA says its Hubble Space Telescope has captured the most detailed and dramatic images ever taken of the distant dwarf planet Pluto.

Space agency astronomers said the images, released Thursday, show an icy, mottled, dark molasses-colored world undergoing seasonal surface color and brightness changes.

"Pluto has become significantly redder, while its illuminated northern hemisphere is getting brighter," NASA said. "These changes are most likely consequences of surface ice melting on the sunlit pole and then refreezing on the other pole, as the dwarf planet heads into the next phase of its 248-year-long seasonal cycle."

Astronomers said the images confirm Pluto is a dynamic world that undergoes dramatic atmospheric changes and is not simply a ball of ice and rock.

"These dynamic seasonal changes are as much propelled by the planet's 248-year elliptical orbit as by its axial tilt," the space agency said, noting Pluto is unlike Earth, where the planet's tilt alone drives seasons.

The space agency said the new Hubble images will remain our sharpest view of Pluto until the New Horizons probe is within six months of its Pluto flyby in 2015.

Officials said the latest images will help planetary astronomers interpret more than three decades of Pluto observations from other telescopes, officials said.

The Hubble images and additional information are available at http://www.nasa.gov/mission_pages/hubble/science/pluto-20100204.html.