Good bye Pluto, we'll miss thee

[TheDruid]

Its official, Pluto is no longer a planet.

http://www.wired.com/news/technology/space/0,71650-0.html?tw=wn_index_5

[Mr. Analog]

It's a Dwarf Planet.

[Darren Dirt]

Stephen Colbert did a funny bit the other day on this issue.

In summary, he was "concerned" that the solar system would go down to "8". So he takes credit for the gathering of the experts, who then changed the rules and the result is we have 3 extra "planets" -- including the former "moon" of Pluto.


Funny stuff:

pt1
http://www.comedycentral.com/sitewide/media_player/play.jhtml?itemId=73146

pt2
http://www.comedycentral.com/sitewide/media_player/play.jhtml?itemId=73145

( I love how he "called it" )

[Darren Dirt]

http://online.wsj.com/public/article/SB115634717941843414-GfO_IzCzgm_cfVjj5_BbtogGqxQ_20060923.html?mod=tff_main_tff_top

THE NUMBERS GUY
By CARL BIALIK

Rethinking the Solar System
August 25, 2006

How did Pluto wake up Thursday as a full-fledged planet but end the day as a "dwarf planet," thanks to a conference of scientists in Prague? What makes a planet a planet? And who are these people tinkering with our solar system?

To answer questions about the change in one of science's most familiar numbers -- the nine planets of our solar system are now eight -- I spoke to several astronomers who didn't attend the International Astronomical Union meeting but were following the debate closely.

David Rabinowitz at Yale and Mike Brown at the California Institute of Technology both participated in the discovery three years ago of the celestial object 2003 UB313 (nicknamed "Xena"), which is larger than Pluto. That finding spurred astronomers to clarify the definition of "planet." Marc Buie, an astronomer at Lowell Observatory in Flagstaff, Ariz., also searches for new objects in the solar system. Here, with their help, are answers to some questions about Pluto's downgrade.

What is the new definition of a planet?

Planets, according to the IAU, orbit the sun, are nearly round and have cleared other objects out of their orbital neighborhoods, either by sucking up the material through gravity or turning the objects into satellites (such as the Earth's moon). You can read the full text of the IAU resolution adopted Thursday.

"Nearly round" would seem to allow for some wiggle room. But, the scientists told me, any object large enough to mount a bid for planetary status would be rounded out by the force of gravity on itself. The "nearly" is there because rapidly spinning, large objects -- such as Saturn -- are flattened out a bit. "But gravity still determines the shape," Dr. Rabinowitz told me. "Gravity makes it as round as possible, given the spinning."

The IAU didn't set a numerical threshold for size. For an object made of typical planetary ingredients, a diameter of 800 kilometers, or about 500 miles, would be enough to ensure gravity could do its rounding. But a denser object could take up less space and still be massive enough.

Why didn't Pluto make the cut?

Pluto, with a diameter of roughly 2,300 kilometers (about 1,430 miles), easily qualifies on size, and it does orbit the sun. But its orbit passes through the Kuiper Belt, and Pluto's orbit isn't clear of other objects.

Dr. Rabinowitz said that this criterion is "the weakest part of the definition," because celestial objects can migrate. "Pluto probably did not form where it is now," he added.

Dr. Buie also criticized this part of the definition: "In the case of the terrestrial planets, did they clear out the inner solar system, or did something else do it? To me, that's kind of fuzzy."

How can we be sure scientists' measurements of the size and orbits of objects in our solar system are correct?

Thanks to the Hubble Space Telescope, launched in 1990, the eight planets and Pluto are well understood, the astronomers told me. The New Horizons spacecraft is expected to deliver even more information about Pluto when it flies by in 2015.

But newer objects are farther away (Xena is three times farther from the sun than is Pluto) and show up far more faintly on astronomers' instruments. "If we find something really quite far away in the solar system, which is where we're looking now, it will have to be big to be seen," Dr. Brown said. "It will be a much harder process to learn about these things."

So we've gone from nine planets to eight. Are we going to find any more planets?

"Oh, yes, that's my hope," Dr. Brown said. "That's where the fun comes in. They've really upped the bar on what something has to be to be a planet. I still want to find a planet." His team uses a high-resolution camera outfitted to a telescope at Palomar Observatory in Palomar Mountain, Calif., that can detect distant objects. That system was used to discover Xena.

Dr. Rabinowitz said the next target is the volume of space 10 billion kilometers to 100 billion kilometers away. It's possible that many large objects remain undetected there, but they reflect so little light that they will be difficult to detect -- and may be found only by more advanced equipment than what is available now.

Who are the scientists behind this resolution? How much weight does it carry?

The International Astronomical Union is an association of professional astronomers founded in 1919 to, in part, designate celestial bodies. More than 2,500 members gathered in Prague this month for the 26th general assembly, held every three years, to discuss their research and settle the planet debate. Each member -- generally astronomers nominated by their national professional associations and selected by the IAU's executive committee -- gets a vote, though just a few hundred members stuck around until the end of the conference to weigh in on the issue.

The group can't force planetarium owners, textbook publishers and others to go along with its findings. "You can ignore it if you wish. We have no authoritative power," IAU Vice President Bob Williams told the Rocky Mountain News earlier this month.

Still, the change may not be as dramatic as it seems, since educators and researchers had already begun to diminish Pluto's role in recent years. "I don't think it will have a major impact on modern textbooks, most of which say there are eight large planets, and Pluto," Dr. Rabinowitz said.

(The Wikipedia entries for Pluto, the Solar System and planet were quickly updated Thursday.)

The previous, ad hoc classification of planets counted Pluto until Thursday, and a week ago scientists were mulling a planetary definition that would have used a different scheme to conclude there are 12 planets. How can the public -- particularly diorama-building school children -- be sure that scientists won't just change the definition again?

Dr. Buie answered with a question: "Will this be a definition that stands up to thousands and thousands of years of scientific scrutiny? Probably not. It will probably outlive us, though."

Dr. Rabinowitz was less certain: "Scientists go from hard beliefs which drive their research into complete upheaval. You have to be flexible as a scientist. I wouldn't be surprised if this definition gets revisited down the line, maybe in five or 10 years."

Michael Shara, curator of astrophysics at the American Museum of Natural History in New York, told me that the new definition is "extremely clean," and said he knew of no celestial bodies whose classification is ambiguous under the new rules. The IAU vote is something of a vindication for the museum, whose Rose Center for Earth and Space has for the last six years classified Pluto as an "ice dwarf" rather than a planet. When that decision was first announced, he said, "There were angry letters of protest from second graders as well as adults who were attached to Pluto."

Ah... Now it all makes sense to me

Actually, it doesn't. "Porcupines" is the last word in the mneumonic. End of story. :-\

[Mr. Analog]

Tactful eulogy:
http://www.solongpluto.com/

[Darren Dirt]

Its official, Pluto is no longer a planet.

http://www.wired.com/news/technology/space/0,71650-0.html?tw=wn_index_5

"I just want to be the first person who comes out and starts The Pluto Truth Movement. Pluto was murdered. By the government."

[Melbosa]

Here's one for all our viewing fans!

[Mr. Analog]

Ha!
http://img2.imagepile.net/img2/47691664.jpg