On Friday night, I was temporarily taken back to the excitement I held in my childhood for all things space-related when the local news announcer declared the discovery of a new planet discovered within our solar system. For more information, check out this news site:
This is the largest object found within our solar system since the discovery of Neptune in 1846. Thanks to NASA making most of their images public domain, I can include the following artist's rendition:
Although there have been debates in recent years as to whether or not Pluto should actually be considered a planet, due to it's small size, it seems that there is less chance that this new discovery should yield as much debate, as it is larger than Pluto at its smallest estimate, and more likely half again as large as Pluto (it will apparently take another 6 months to determine its actual size with any reliability). It is about three times the distance from the sun of Pluto, and has an orbit that is even more skewed off the plane that most of the other planets (excepting Pluto) travel around the sun.
The discoverers of this "Tenth Planet" have submitted a name to the International Astronomical Union, but it has not yet been officially released to the public. Rumors are surfacing that astronomers are calling the planet "Xena," but it is not confirmed that this is the name submitted to the IAU, nor that the name has been officially approved at all. For now, "2003 UB313" will have to do.
(The mischevious Dr. Who fan in me humbly suggests "Mondas.") :)