Theos-Talk Archives (July 2005 Message tt00226)

Dallas,
Didn't HPB say something about an as yet undiscovered planet? I have searched for the quote but cannot find it.
Cass

Puny Pluto gets big brother
It's a planet!

By Jeremy Manier
Tribune staff reporter
Published July 30, 2005

Larger than Pluto and far beyond its orbit, shining so brightly an amateur stargazer could have spotted it years ago, there is a 10th planet, astronomers announced late Friday.

Calling the still-unnamed world a planet likely will stir intense debate among some astronomers who argue that even tiny Pluto would not be called a planet were it discovered today.

But if Pluto counts as a planet with a width of about 1,400 miles, the new world--which may be up to twice as big--also belongs on the list, said Mike Brown, leader of the team that made the discovery.

"Get your pens; start rewriting the textbooks today," said Brown, a professor of planetary science at the California Institute of Technology who has hunted for such an object for more than five years.

For now the would-be planet goes by the unwieldy designation of 2003UB313. Brown said his team has proposed a more melodious name to the Paris-based International Astronomical Union and is waiting for approval before making it public.

The planet is now 9 billion miles from the sun--more than twice as distant as Pluto at its farthest point--and takes 560 years to make one orbit. It would be the first planet discovered in our solar system since astronomer Clyde Tombaugh found Pluto in 1930.

Larry Lebofsky, a senior research scientist at the University of Arizona's Lunar and Planetary Laboratory who was not involved in the finding, agreed with Brown that the object deserves planetary status.

"I like the idea that somewhere along the line humans defined Pluto as the limit of what we call a planet," Lebofsky said. "If you find something larger, there's no reason why that shouldn't count too."

Brown made a rushed announcement late Friday at NASA's Jet Propulsion Laboratory in California, after his team realized someone had hacked into their Web site and accessed the crucial data, apparently with the goal of making it public. It was "someone with more cleverness than scruples," Brown said. "It's not the way we'd prefer to do it, but that's the way it happened."

Because the team had not finished analyzing the planet, they still do not know precisely how large it is. Astronomers gauge the size of such distant objects by measuring their brightness; if a distant object is still very bright, it must also be large. Brown said 2003UB313 is so bright and so far away that even if its surface were extremely reflective, the world would have to be larger than Pluto. At most, it may be twice Pluto's size.

"We expect it's about 1 1/2 times larger," Brown said.

Brown's team had known about the object since Jan. 8, when they detected it using the relatively small 48-inch Samuel Oschin Telescope at Mt. Palomar in California. The telescope uses a 180-megapixel digital camera with the widest field of view of any astronomical camera, which lets the team survey huge swaths of sky at once.

Like Pluto, the new object orbits the sun at a strange angle--in the case of the new world, about 44 degrees off the plane where the other planets move. It also follows a highly irregular orbit, swinging in almost to the circuit of Neptune at its closest point. Brown said an amateur could see the object with a 14-inch telescope; in North America it is now visible almost directly overhead at dawn.

The team had used its telescope for years to search for objects in the Kuiper Belt, a broad disk of icy bodies in the expanses of space beyond Pluto. Last year Brown's group found Sedna, an object about three-fourths the size of Pluto and whose irregular orbit extends far beyond that of 2003UB313.

On Thursday, astronomers in Spain announced the discovery of another large Kuiper Belt object, which Brown's group had tracked as well. Brown said Friday that his team's observations indicate that world is about the same size as Sedna

The presence of so many Pluto-like worlds at the outer expanses of the solar system has prompted some astronomers to argue that Pluto--less than half the size of the next smallest planet, Mercury--is an unremarkable hunk of ice that doesn't belong with either the rocky planets close to the sun or the gas giants beyond.

In 2000 the American Museum of Natural History demoted Pluto by leaving it out of a display of the planets, though other museums have not taken such drastic steps. The International Astronomical Union still classifies Pluto as a planet.

Brown confessed he used to be among those who thought Pluto never deserved planetary clout. But he said he has come to believe that on this question, what ordinary people think is as important as the technical judgment of astronomers.

"People love Pluto," Brown said. "Calling Pluto not a planet is never going to be a popular decision. It seems reasonable if that Pluto is a planet and you've got something bigger and farther, you'd better call that a planet too."

By that standard, the new world's acceptance as a planet may hinge on whether the public warms up to it.

"Maybe it depends on what name they came up with," Lebofsky said.

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jmanier@tribune.com 






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