Tuesday, April 11, 2006


Xena, Kuiper Belt Princess?

While looking up information on moonquakes, I came across this story about the 10th planet in our solar system.
NASA's Hubble Space Telescope has resolved the "tenth planet," nicknamed "Xena," for the first time and has found that it is only just a little larger than Pluto.

Previously, Xena was thought to be about 30% larger, based on its brightness.
Because Xena is smaller than earlier thought, but comparatively bright, it must be one of the most reflective objects in the solar system. The only object more reflective is Enceladus, a geologically active moon of Saturn whose surface is continuously recoated with highly reflective ice by active geysers.

Xena's bright reflectivity is possibly due to fresh methane frost overlying the surface. It is possible that Xena had an atmosphere when it was closer to the Sun, but "froze out" at its current large distance, and material settled on its surface as frost.

Another possibility is that Xena is also continuously leaking methane gas from its warmer interior. When this methane makes it to the cold surface it immediately freezes solid, covering craters and other features to make this Kuiper Belt object (KBO) uniformly bright to Hubble's telescopic eye.

Of course, the debate over whether Xena (or even Pluto) should be considered a planet is far from settled, since there is no good consensus on what exactly constitues a planet. It seems that if Pluto is considered a planet, then based on its size, Xena should be too.

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