A moon for 2003 UB313?

If you remember back to the long distant past of July, you will remember the discovery of a possible tenth planet. It still goes by the name 2003 UB313, but Mike Brown (one of the co-discoverers) has updated his web page to say that, just like 2003 EL61, it appears to have its own moon. How cool is that?

The moon currently goes by the even snappier name S/2005 (2003 UB313) 1, but Mike Brown and co-workers are using the code name Gabrielle (to go with Xena) as it is easier to say. Here is the latest image of the pair taken using the adaptive optics system at the W.M. Keck Observatory:

2003 UB313 and moon
The planet appears in the centre, while the moon is the small dot to the right (3 o'clock). CREDIT: W.M. Keck Observatory

Mike Brown rules out the dot being a star as it moves with 2003 UB313. In fact, the line at the bottom is a star that has been smeared out because the camera was following 2003 UB313. Another worry was that it could have been an artefact of the adaptive optics system. However, if that was the case, Mike says that it should create an arc around UB313 during the course of one night.

Finding a moon is important because it allows the mass (how much stuff there is) of UB313 to be calculated. All you need to do is work out how long the moon takes to complete one orbit and know how far it is from the bigger body. You could work out the mass of the Sun using the Earth in a similar way - science is great like that!

Posted in astro blog by Stuart on Sunday 02nd Oct 2005 (10:16 UTC) | Permalink
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