Astronomy Down Under

Of planets and moons

3 Oct at 10:54 by Wilson

Interesting developments in the outer solar system: it turns out that 2003 UB₃₁₃, the possible 10th planet (code-name “Xena”), has a moon. That body, which I discussed in a previous post, is larger than Pluto and orbits the Sun in such a way as to intersect Pluto’s orbit, which makes it the most similar body to other planets that was discovered so far.

The moon doesn’t have a name yet (it was discovered less than a month ago, on 10 September) and is officially known only as “S/2005 (2003 UB₃₁₃)”. The discoverers are calling it “Gabrielle”, though (understandably). Its discovery is very important because it will help astronomers to find out how massive “Xena” is by studying the way the moon orbits the main body.

Oddly enough, the discovery of a moon around it doesn’t mean that “Xena” has any more hope of being called a planet than it had before. Many other bodies in the solar system have moons around then, including several small asteroids in the belt between Mars and Jupiter.