I'm A Sucker for Space and Science News

Scientists Discover 10th Planet's Moon
By ALICIA CHANG
AP Science Writer

LOS ANGELES - The astronomers who claim to have discovered the 10th planet in the solar system have another intriguing announcement: It has a moon.

While observing the new, so-called planet from Hawaii last month, a team of astronomers led by Michael Brown of the California Institute of Technology spotted a faint object trailing next to it. Because it was moving, astronomers ruled it was a moon and not a background star, which is stationary.

The moon discovery is important because it can help scientists determine the new planet's mass. In July, Brown announced the discovery of an icy, rocky object larger than Pluto in the Kuiper Belt, a disc of icy bodies beyond Neptune. Brown labeled the object a planet and nicknamed it Xena after the lead character in the former TV series "Xena: Warrior Princess." The moon was nicknamed Gabrielle, after Xena's faithful traveling sidekick.

By determining the moon's distance and orbit around Xena, scientists can calculate how heavy Xena is. For example, the faster a moon goes around a planet, the more massive a planet is.

But the discovery of the moon is not likely to quell debate about what exactly makes a planet. The problem is there is no official definition for a planet and setting standards like size limits potentially invites other objects to take the "planet" label.

Possessing a moon is not a criteria of planethood since Mercury and Venus are moonless planets. Brown said he expected to find a moon orbiting Xena because many Kuiper Belt objects are paired with moons.

This is just a cool thing. As long as we have been looking at the solar system, to discover a new orbiting body, no matter how small, is just neat. The more we explore, the more we find out how little we really know and how much more there is to discover.

Full Story: New Moon

What do you think?

To leave your opinion click on the word "COMMENT(S)" below