Introducing... the 10th planet!

I started hearing about this Friday afternoon on some space science newsgroups I was on, and by this evening they'd literally erupted with news. It'll be all over the media by Saturday, but what I guarantee will be overlooked or mangled is the fact that not one, but three planet-sized Trans-Neptunian Objects have been found! Mike Brown, operating out of the Palomar Observatory, has a site up with information about the TNO they're officially calling 2003 UB313 for now (but on the sly, they're calling it Lila). And, oh, here's a picture of the little tyke:



Two days ago, a Spanish team under the leadership of Jose Ortiz reported 2003 EL61. Early on, it had the potential to be larger than Pluto, but then a moon was discovered orbiting it, which altered the equations and reduced EL61's size to roughly a third of Pluto's. It's located at a distance of 51 A.U. from the sun, and the satellite around EL61 has a 49-day orbital period, if you were curious.

The third TNO, provisionally named 2005 FY9, also had a possible size range that exceeded Pluto's, but measurements from NASA's space-bases Spitzer telescope appear to indicate 2005 FY9 is indeed slightly smaller than Pluto as well.

So what about 2003 UB313 then? According to Mike Brown, it is unequivocally larger than Pluto in diameter, but no larger than twice Pluto's diameter. This raises an interesting point that I think will be overlooked in the following days. People are going to fixate on Pluto's diameter of 2,300 km. But Mercury has a diameter of 2,439 km, and Mars has a dimeter of 3,397. If UB313 has a diameter merely half again as much as Pluto--splitting the difference between the maximum and minimum range--then there's a planet the size of Mars out there in the icy nether regions of the solar system. All of those astronomers who try to claim Pluto isn't really a planet because it's really just a large TNO will be hard-pressed to dismiss this one via the same logic.

Things we know already about UB313: It has a 560-year orbit that is tilted a steep 44 degrees to the eliptic. Plus, its orbit is highly eccentric. The world is currently 97 A.U. from the sun (making it the most distant object in the solar system, period) but at perihelion it is only 35.5 A.U. out. For the sake of comparison, Pluto's aphelion is 49 A.U. and perihelion is 29 A.U. Wow.

As for the planet's formal name, Persephone has already been suggested...

Now Playing: Monks of the Benedictine Abbey el Calcat with Boy's Choir from L'Alumnat A Treasury of Gregorian Chants