10th Planet Identified?

From Sky and Telescope:

After 75 years of speculation and false leads, it finally seems to have happened. A team of astronomers using the 48-inch Samuel Oschin Telescope at Palomar Observatory and the 8-meter Gemini North telescope on Mauna Kea, Hawaii, has discovered the largest Kuiper Belt object (KBO) ever.

It is bigger than Pluto, the 9th planet.

While the headline I read to this article referred to the object as a planet, the text refers to it as a Kuiper Belt Object partly because intense debate is ongoing regarding what exactly constitutes a planet.  Many astronomers do not consider Pluto a planet. 

At the other end of the size spectrum, tiny Pluto should never have been called a planet in the first place, most mainstream scientists agree.

Pluto is less than half the size of any other planet, and its orbit is at a distinct angle from the plane in which the other planets travel around the Sun. Most significant, Pluto roams so far beyond the orbit of Neptune that researchers say it is part of the Kuiper Belt, a region of distant, frozen rocks only confirmed to exist in 1992.

"If we'd known about the Kuiper Belt when Pluto was discovered [in 1930], it would have been a giant Kuiper Belt Object," said Michael A'Hearn, a University of Maryland astronomer and past president of the IAU's Planetary Systems Sciences division.

So we might have 10 planets or we may only have 8... or maybe 9 (not including Pluto).  Even so, this is a cool find.

Update:  Kindred Spirit William Polley has some more information and some pictures here.

Comments

[William Polley]

Phil,

I posted NASA's images over at my site. Very cool.

Bill