New 'Planet' Is Bigger Than Pluto
By ALICIA CHANG, AP
LOS ANGELES (Feb. 1) - Scientists say they have confirmed that a so-called 10th planet discovered last year is bigger than Pluto, but that likely won't quell the debate over what makes a planet.
The astronomers who spotted the icy, rocky body - informally called UB313 - had reported only a rough estimate of its size based on its brightness.
But another group of researchers has come up with what is believed to be the first calculation of UB313's diameter - 1,864 miles.
By measuring how much heat it radiates, German scientists led by Frank Bertoldi of the University of Bonn estimated that UB313 was about 1,864 miles across. That makes it larger than Pluto, which has a diameter of about 1,429 miles.
"It is now increasingly hard to justify calling Pluto a planet if UB313 is not also given this status," Bertoldi said in a statement.
Details were published in Thursday's issue of the journal Nature.
Apparently this month, scientists will use Hubble Space Telescope (HST) to make additional measurements of Pluto and its 'partners'. The objective is to add data to what has already been collected in order to confirm that there are indeed other small bodies out there.
From
www.Stardate.org, February 1, 2006
Since its discovery in 1930, Pluto has remained an aloof little world. It's so small and far away that it appears as nothing more than a dot in even the largest telescopes. It has a moon that's about half as big as Pluto, but it wasn't discovered until 1978. And it may have a couple of more moons that were discovered just last year. Astronomers will hunt for those moons with Hubble Space Telescope this month.
Hubble detected the possible moons in a series of pictures it snapped three days apart back in May. The images showed a couple of tiny points of light near the planet. It's unlikely that they're stars or other background objects. But the team of astronomers that made the observations wants to check one more time. If the objects are still there, astronomers will confirm that Pluto has three moons, not one.
Pluto is a member of the Kuiper Belt -- a broad ring of icy bodies that orbits the Sun outside the orbit of the planet Neptune. Pluto was the first member of the belt ever discovered. But in recent years, astronomers have discovered hundreds of Kuiper Belt objects -- including some that are close to the same size as Pluto.
These discoveries have created some chaos in how astronomers classify planets. Some want to take Pluto off the list of planets, while others want to add the biggest of the newly found Kuiper Belt objects. Pluto's new moons will add to the debate, as astronomers ponder what to do with this aloof little world.
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