Brilliant! Tenth planet turns out to be a shiner

By Aussiegirl

The latest news about Xena, the new planet on the block. I like the scientifically precise language in this quote from the article: What's the heat source that could drive such activity? "Beats me," says planetary scientist Rick Binzel.

Brilliant! Tenth planet turns out to be a shiner: Science News Online, April 15, 2006

Xena, unofficially called the 10th planet, is the second-most-shiny known object in the solar system, new observations show. Scientists are scrambling to explain where Xena got its sparkle. Some suggest that it might have enough heat to belch methane, despite being in the coldest region of the solar system.

The relatively small size shown in those images indicates that the body reflects 86 percent of sunlight. Brown says he was "thoroughly shocked" by that finding. Researchers had assumed that Xena's surface was similar to that of Pluto, which reflects 60 percent of sunlight.

[...] Scientists have proposed two scenarios to explain Xena's high reflectivity. In one, a jet of methane leaks continuously from Xena. The methane jet freezes as it emerges, continually blanketing the surface with fresh snow.

What's the heat source that could drive such activity? "Beats me," says planetary scientist Rick Binzel of the Massachusetts Institute of Technology. He notes that gravitational tugs from a neighboring moon sometimes generate heat within a body, but Xena's moon is too small to do that.

Another source of heat, sunlight, would penetrate only a few tens of meters below Xena's surface and would probably have long ago depleted the reserves of methane there.