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Tenth Planet Has a Moon

September 30, 2005

PASADENA, Calif. --The newly discovered 10th planet, 2003 UB313, is looking more and more like one of the solar system's major players. It has the heft of a real planet (latest estimates put it at about 20 percent larger than Pluto), a catchy code name (Xena, after the TV warrior princess), and a Guinness Book-ish record of its own (at about 97 astronomical units-or 9 billion miles from the sun-it is the solar system's farthest detected object). And, astronomers from the California Institute of Technology and their colleagues have now discovered, it has a moon.

The moon, 100 times fainter than Xena and orbiting the planet once every couple of weeks, was spotted on September 10, 2005, with the 10-meter Keck II telescope at the W.M. Keck Observatory in Hawaii by Michael E. Brown, professor of planetary astronomy, and his colleagues at Caltech, the Keck Observatory, Yale University, and the Gemini Observatory in Hawaii. The research was partly funded by NASA. A paper about the discovery was submitted on October 3 to Astrophysical Journal Letters.

http://pr.caltech.edu/media/Press_Releases/PR12744.html

"Like Pluto, the new planet is a member of the Kuiper belt, a swarm of icy bodies beyond Neptune in orbit around the sun. Until this discovery Pluto was frequently described as "the largest Kuiper belt object" in addition to being called a planet. Pluto is now the second largest Kuiper belt object, while this is the largest currently known."

Interesting article debating as to whether or not Pluto is a planet; or what constitutes a planet by definition. Culturally Pluto IS a planet, scientifically it may not be.
~"The discovery of Xena, as an addition to our Solar System, has prompted astronomers to fast-track plans to decide what is and is not a planet. The rules, which could be formulated by International Astronomical Union (IAU), could more than double the number of local planets - or they could demote Pluto, leaving us with only eight in our neighbourhood."

http://www.nature.com/news/2005/050801/pf/050801-2_pf.html

Sincerely,

http://www.gps.caltech.edu/~mbrown/planetlila/

Many thanks for the link Mung, hopefully IAU will resolve this by the weekend.

Very intersting stuff!

If it has a moon, it should be well on its way to being declared a planet.

The discovery of new planets, or almost planets, is very interesting. The same group discovered an object almost the size of Pluto that they called Sedna. Most likely Sedna has no moon.
http://www.nasa.gov/vision/universe/solarsystem/planet_like_body.html.

Xena from what I read is no where near as far away as Sedna which is estimated to be at its farthest at 84 billion miles from the sun. I have been anxious to get some workable details on the new discoveries but none yet.

Assuming that Xena semi major axis is 9,000,000,000 miles than we can estimste an orbital velocity of 1.88 miles per second (3 Km) and that the orbit takes about 953.15 earth years for Xena to make one complete revolution around the sun. I have not found a statement for the estimated radius of Xena that is offered with any confidence and that applies to the moon as well. When it is available it will be fun to try and work out the balance of Xena statistics.

They estimate that Sedna, much farther out than xena, takes about 10,500 earth years to make one complete revolution. For example, Pluto only take about 248 earth years for one complete revolution around the sun.

Jim Wood