Posted on 10/19/2010 2:41:48 PM PDT by SunkenCiv
The Geminid meteor shower, which peaks each year in December... are *not* caused by debris left behind from an active comet... Until recently, the favored view of Phaethon was that it's a dead comet -- the rocky core of a "dirty snowball" that lost its ices after too many close encounters with the sun.
...
In June 2009 astronomers using the STEREO sun-watching probe suddenly saw the rocky body flare to life as it neared the sun, brightening by a factor of two... So, not so dead after all. But that brings us back to figuring out what exactly Phaethon is, and why it's spewing material like a comet.
...researcher Humberto Campins of the University of Central Florida... pegged Phaethon as an asteroid... the orbiting body has hydrated minerals, aka clays, on its surface. So far, no known comets contain clays. Based on its spectrum, "to me Phaethon looks like Pallas," Campins said.
A more detailed analysis showed that the body does in fact share certain chemical signatures with Pallas, a roughly 326-mile-wide (525-kilometer-wide) primitive asteroid in the main belt between the orbits of Mars and Jupiter.
...
If the Geminids are the spawn of Pallas, their meteorites could teach us a lot about that huge and hard-to-reach parent body... Now, even if we accept Phaethon as a Pallas family member, there's still the question of why it's an oddly active asteroid... Heating carbonates to very high temperatures, like those reached on the surface of Phaethon as it nears the sun, can make such minerals explode.
(Excerpt) Read more at blogs.nationalgeographic.com ...
 |
||
| · join · view topics · view or post blog · bookmark · post new topic · subscribe · | ||
Good call, I’ll add tvf keywords.
Cue the skeet shooting jokes in 3...2...1...
I’ve never heard an asteroid called “primitive” before. What is that contrasted with? A civilized asteroid?
;’)
I saw one today, Palin asking for another Obama clay pigeon, something like that. :’D
I think it has to do with the surface being pristine, but if this new idea is on the ball, then the surface ain’t pristine. Luckily, it’s only the writer, not the scientist. :’)
some pics:
http://newsroom.ucla.edu/portal/ucla/artwork/1/1/1/6/3/111163/Pallas_figure_3_image-prv.jpg
http://transientsky.files.wordpress.com/2010/02/hst_pallas.jpg
Pallas Asteroid May Be Protoplanet
Posted on: Monday, 12 October 2009, 10:20 CDT
http://www.redorbit.com/news/space/1768096/pallas_asteroid_may_be_protoplanet/
Asteroid Pallas is Also a Protoplanet
http://www.universetoday.com/42540/asteroid-pallas-is-also-a-protoplanet/
more:
http://www.google.com/search?q=pallas+asteroid
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.
