Posted on 04/19/2006 4:50:42 PM PDT by neverdem
Xena, unofficially called the 10th planet, is the second-most-shiny known object in the solar system, new observations show. Scientists are scrambling to explain where Xena got its sparkle. Some suggest that it might have enough heat to belch methane, despite being in the coldest region of the solar system.
The new notion of Xena arises from Hubble Space Telescope images that were released this week. The images reveal that Xena, the most distant known object in our solar system, isn't quite the big shot that scientists had thought it was.
The chilly outpost's diameter—2,384 kilometers—makes it about 5 percent larger than Pluto, Mike Brown of the California Institute of Technology in Pasadena and his colleagues announced April 11. That's still large enough for Xena to retain its unofficial status as a planet, Brown says, but considerably smaller than ground-based observations had indicated (SN: 8/6/05, p. 83: http://www.sciencenews.org/articles/20050806/fob2.asp).
Researchers have difficulty determining the size of remote denizens of the solar system because a large object that reflects a small amount of sunlight looks the same as a small object reflecting a lot of light.
But for Xena, the sharp Hubble pictures erase that ambiguity.
The relatively small size shown in those images indicates that the body reflects 86 percent of sunlight. Brown says he was "thoroughly shocked" by that finding. Researchers had assumed that Xena's surface was similar to that of Pluto, which reflects 60 percent of sunlight. Saturn's moon Enceladus, recently shown to be shooting out a geyser of water vapor (SN: 1/7/06, p. 13: Available to subscribers at http://www.sciencenews.org/articles/20060107/note11.asp), is the only solar system object known to have a higher reflectivity, notes Brown.
Scientists have proposed two scenarios to explain Xena's high reflectivity. In one, a jet of methane leaks continuously from Xena. The methane jet freezes as it emerges, continually blanketing the surface with fresh snow.
What's the heat source that could drive such activity? "Beats me," says planetary scientist Rick Binzel of the Massachusetts Institute of Technology. He notes that gravitational tugs from a neighboring moon sometimes generate heat within a body, but Xena's moon is too small to do that.
Another source of heat, sunlight, would penetrate only a few tens of meters below Xena's surface and would probably have long ago depleted the reserves of methane there.
In the other model, the planet has a methane-rich atmosphere created during the portion of its 560-year-long orbit when it's nearest the sun. As Xena speeds away, the atmosphere freezes on the surface as a bright frost. However, Brown says, it's not clear that such frost would be bright enough to account for the shininess of Xena's surface.
| If you have a comment on this article that you would like considered for publication in Science News, send it to editors@sciencenews.org. Please include your name and location. |
|
To subscribe to Science News (print), go to https://www.kable.com/pub/scnw/ subServices.asp.
To sign up for the free weekly e-LETTER from Science News, go to http://www.sciencenews.org/pages/subscribe_form.asp.
References:
2006. Hubble finds that the 'tenth planet' is slightly larger than Pluto. Space Telescope Science Institute news release. April 11. Available at http://hubblesite.org/newscenter/newsdesk/
archive/releases/2006/16/full/.
Further Readings:
Cowen, R. 2006. Moon spray. Science News 169(Jan. 7):13. Available to subscribers at http://www.sciencenews.org/articles/20060107/note11.asp.
______. 2005. Bigger than Pluto: Tenth planet or icy leftover?. Science News 168(Aug. 6):83. Available at http://www.sciencenews.org/articles/20050806/fob2.asp.
For additional images and background material about Xena, go to http://hubblesite.org/newscenter/newsdesk/
archive/releases/2006/16/.
For additional background information about Xena from Mike Brown, go to http://www.gps.caltech.edu/~mbrown/planetlila/.
A version of this article written for younger readers is available at Science News for Kids.
Sources:
Richard Binzel
Massachusetts Institute of Technology
Department of Earth and Planetary Science
77 Massachusetts Avenue
Mailstop Code 54-410
Cambridge, MA 02139-4301
Michael Brown
California Institute of Technology
Division of Geophysics & Planetary Science
Mailstop Code 150-21
Pasadena, CA 92215
http://www.sciencenews.org/articles/20060415/fob8.asp |
|
|
|
|
From Science News, Vol. 169, No. 15, April 15, 2006, p. 230. |
|
|
|
|
Copyright (c) 2006 Science Service. All rights reserved. |
|
The Frozen Flatulence Effect?
No problem. Interest in this story is gaining momentum. IRC Time or Newsweek ran a small piece on the contraversy surrounding Pluto as a moon of Neptune because of Neptune's influence on Pluto. Meanwhile, the article suggests the asteroid Ida that orbits between Mars and Jupiter could be technically designated a planet or planetoid with a moon as per the Galileo pass in 1993. They also touched on the subject that some of the moons of jupiter and Saturn should actually be termed planets/planetoids under certain criteria.
IIRC, the article suggested that the solar system may have as many as 15 or more planets. Some of the orbits of these objects are radical compared to the Earth's. One object, mentioned in a cited thread, is UB313 which has the body cutting in front of the well-known planets and then out into deep deep space.
Some of the bodies discovered within the past six years revolve around SOL every 10,000 or more earthyears! imagine that birthday celebration.
Rich, white American males, most likely, though the exact mechanism by which this is accomplished remains to be invented.
In keeping with the new trend of naming planets after characters on crappy WBNetwork television shows, the 12th planet will be named "Screech."
Well, let's rename it. I propose Orbital Sphere X... which is shaped like an Apple... Of course we can abreviate the large words ... and come up with a nice new name, derived completely fairly:
Apple OS X...
Good name for the tenth planet... its X for ten, X for unknown and refers to its shape and brightness.
Now, no one could possible say that the name is refering to a commercial product, say like the name "Xena" refers to a commercial Television Program franchise... ;^)>
Hey, that can be pretty fun you know--until you have to mow it.
Ummmm, okay! I'll just take your word for it! :P
Nice graphic!
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
