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In Deep Space, a Cosmic Pileup

By CLARA MOSKOWITZ
,
Space.com
posted: 3 HOURS 17 MINUTES AGO
comments: 82
filed under: Science News
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Space.com
(Aug. 11) - Two distant planets orbiting a young star apparently smashed into each other at high speeds thousands of years ago in a cosmic pileup of cataclysmic proportions, astronomers announced Monday.
Telltale plumes of vaporized rock and lava leftover from the collision revealed its existence to NASA's Spitzer Space Telescope, which picked up signatures from the impact in recent observations.
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colliding planets
NASA/JPL-Caltech

Astronomers have found evidence that a celestial body about the size of our moon slammed into a planet the size of Mercury within the last few thousand years. The cosmic collision is seen here in an artist's conception.

The two-planet pileup occurred within the last few thousand years or so - a relatively recent cosmic timeframe. The smaller of the two bodies - a planet about the size of Earth's moon, according to computer models - was apparently destroyed by the crash. The other was most likely a Mercury-sized-planet and survived, albeit severely dented.
"This collision had to be huge and incredibly high-speed for rock to have been vaporized and melted," said Carey Lisse of the Johns Hopkins University Applied Physics Laboratory in Maryland, lead author of a paper describing the findings in the Aug. 20 issue of the Astrophysical Journal.
Researchers believe the planets were moving at about 22,400 mph (10 kilometers per second) before the crash. The violent wreck released amorphous silica rock, or melted glass, and hardened chunks of lava called tektites. Spitzer also spotted large clouds of orbiting silicon monoxide gas created when the rock was vaporized.
"This is a really rare and short-lived event, critical in the formation of Earth-like planets and moons," Lisse said. "We're lucky to have witnessed one not long after it happened."
Infrared detectors on Spitzer found the traces of rocky rubble and re-frozen lava around a young star, called HD 172555, still in the early stages of planet formation. The system is about 100 light-years from Earth. One light-year is the distance light travels in a year six trillion miles (9.7 trillion km).
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A similar fender-bender is thought to have formed Earth's moon more than 4 billion years ago, when a body the size of Mars rammed into Earth.
"The collision that formed our moon would have been tremendous, enough to melt the surface of Earth," said co-author Geoff Bryden of NASA's Jet Propulsion Laboratory in California. "Debris from the collision most likely settled into a disk around Earth that eventually coalesced to make the moon. This is about the same scale of impact we're seeing with Spitzer - we don't know if a moon will form or not, but we know a large rocky body's surface was red hot, warped and melted."
In fact, such violent encounters seem to have been common in our own solar system's early history. For example, giant impacts are thought to have stripped Mercury of its outer crust, tipped Uranus on its side, and spun Venus backward.
As recently as last month, a small space rock slammed into Jupiter, making a large black bruise.
In general, rocky planets like Earth coalesce and grow when small rocks crash and clump together, merging their cores.
The system around HD 172555 is a relative baby at only 12 million years old, compared to our solar system's age of 4.5 billion years.
© Imaginova Corp. All rights reserved.
2009-08-11 11:39:15
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Agilejbk

04:12 PMAug 11 2009

I am in awe of what goes on in the Cosmos. Further, how we can tell or fairly accurately "piece together" what may have occurred many years ago also fascinates me greatly. But even in the vastness of space, these collisions do occur- even as infrequently as hundreds of thousands of years. We certainly need to keep watching the heavens.

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ERIESLOOP1

04:12 PMAug 11 2009

Some science is speculation based on certain "laws"...and at such distances we're resigned to making open-ended statements perhaps akin to "educated guesses". But science will move forward bit by bit as technology catches up to our curiosity. Still, I have absolute faith in the process, as opposed to faith in fantastical miracles as demanded by religion.

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Kidzark

04:12 PMAug 11 2009

WOW Aeolianite you are the smartest man I have ever heard speak-your ideas are perfact and everybody else is stupid-I am so glad to know you think so highly of yourself --go make a solor system and I really be impressed!!

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DavidoffM

04:09 PMAug 11 2009

HBurns1351 Thanx for the info

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Black2Deep

04:07 PMAug 11 2009

WEESTIMATE 03:56 PMAug 11 2009 Looks like what's happening with the healthcare bill and the American people--------------------Do they pay you to troll the boards and post this crap or are you just stupid?

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HBurns1351

04:07 PMAug 11 2009

DavidoffM04:01 PMAug 11 2009Wait a minute. Since when can we see a planet 100 light years away. I know we can detect them by watching a star wabble, but to talk about the small amount of gas and rock and light a mercury sized planet has, is something I never heard of before.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~H B; Heat. Spitzer sees heat. Spitzer is designed to detect infrared radiation. It detected the heat of the collision and the residual heat that remains.

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DavidoffM

04:01 PMAug 11 2009

Wait a minute. Since when can we see a planet 100 light years away. I know we can detect them by watching a star wabble, but to talk about the small amount of gas and rock and light a mercury sized planet has, is something I never heard of before.

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WEESTIMATE

03:56 PMAug 11 2009

Looks like what's happening with the healthcare bill and the American people

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Newjeff121

03:54 PMAug 11 2009

guess assume perhaps

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Aeolianite

03:45 PMAug 11 2009

Jjpalazzini 03:30 PMAug 11 2009 Aeolianite, I am a physicist and I've experienced the same thing. The reason is that religious delusion is the #1 form of mental illness on the planet. Vestiges of a scientifically ignorant and easily frightened population have permeated our society, to the point that the general population prefers to accept an outrageous, superstitious, irrational explanation rather than a reasonable, rational, scientific one based on facts. The bulk of trhe American public is very ignorant. ***************** I think you're right about the fear thing. It seems to me that most people can't handle the uncertainty inherent in science. They prefer a false sense of security that comes from black and white, right and wrong, us and them fundamentalist extremism.

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Two distant planets orbiting a young star apparently smashed into each other at high speeds thousands of years ago in a cosmic pileup of cataclysmic proportions, astronomers announced Monday. Telltale plumes of vaporized rock and lava leftover from the collision revealed its existence to NASA\'s Spitzer Space Telescope, which picked up signatures from the impact in recent observations.