Saturday, 4 October 2008

When Worlds Collide

From the Daily Telegraph:
Two planets about 300 light years from Earth have slammed into each other recently, US astronomers say, the first time evidence of such a catastrophic collision has been seen by scientists.

Astronomers from the University of California, Los Angeles (UCLA) and the California Institute of Technology (CALTECH) said the crash involved two planets orbiting a star in the Aries constellation.

The collision was uncovered while astronomers were attempting to measure the star's age, and found an unusually large amount of dust orbiting the star.

"It's as if Earth and Venus collided with each other," said Benjamin Zuckerman, UCLA professor of physics and astronomy.

"Astronomers have never seen anything like this before. Apparently, major catastrophic collisions can take place in a fully mature planetary system.
This is not good news. Chaos Theory did strongly suggest the possibility that nice, stable, mature, not-rocking-the-boat solar systems could, sometimes, once in a blue moon have this happen. Systems like ours, in fact.

The odds that it would happen before the Sun turns into a Red Giant aren't high. And besides which, we already had our share when the Earth was new, and a planetary collision turned our place into a double planet system. Well, that's the best theory we have for the formation of the Moon.
The collision was an "ultimate extinction event" that would have wiped out any life on either planet in minutes, the report said.
I'm not sure of that - and I don't mean a technologically capable life-form escaping in spacecraft, either - though that possibility can't be entirely discounted either. No, I mean extremophiles - bacteria that live kilometres down in the rock.

Such a collision would lead to dust, debris, and even great chunks of rock being catapulted from the explosion. And they just might survive long enough to find a new home.
Tennessee State University astronomer Gregory Henry said scientists in the United States and France have long studied the stability of planetary orbits.

"Their computer models predict planetary motions into the distant future and they find a small probability for collisions of Mercury with Earth or Venus sometime in the next billion years or more," Henry said.

Prof Zuckerman noted, however, that collisions have occurred in our solar system's past.

"Many astronomers believe our moon was formed from the grazing collision of two planetary embryos, the young Earth and a body about the size of Mars, a crash that created tremendous debris, some of which condensed to form the moon and some of which went into orbit around the young sun," he said.
We need to hedge our bets. Not be stuck on a rock that, while a nice place to live, has no collision insurance.

1 comment:

Lloyd Flack said...

We are probably descended from extremophiles that survived the Late Heavy Bombardment by sheltering deep within the crust. There is some evidence that life may have formed as early as 4.2 billion years ago, well before the Late Heavy Bombardment.