Watch that Rock!

Timothy Birdnow

So, where did that dinosaur-killing rock come from? Researchers have tried to chart it's path.

From the Smithsonian article:

Some of the Oort Cloud comets are often big, between 10 and 37 miles across. And, Siraj noticed, when such large chunks of rock pass close enough to the sun, its massive gravitational forces can tear the rocks into smaller chunks. Those chunks might not be small in an absolute sense. Some can still be miles across, just like the one that struck the Earth 66 million years ago.

Both the sun and the planet Jupiter are so large that their gravity alters the orbits of comets that pass towards the middle of our solar system. Jupiter’s massive gravitational field sometimes disrupts their orbit and sends them closer to the sun. The overall effect, Siraj says, is "like a pinball machine.”

Some of these rocks passing close to the sun, Siraj says, "produce fields of cometary shrapnel.” The breakup of the comet Shoemaker-Levy 9 is an example of just this sort of interstellar interaction. This comet was pulled apart by Jupiter’s gravity in 1992 before the pieces crashed into the planet in 1994.

Not that all experts agree with this new model. Asteroid expert Bill Bottke of the Southwest Research Institute says that events like Shoemaker-Levy 9 may have more stringent requirements than the new model suggests. Further, Bottke says, the model predicts that other planets in the solar system should show signs of these large impacts through time.

Siraj responds that time is a critical factor, with the new model focusing on objects that don’t immediately crash into Jupiter but make their way further into the solar system. And, Siraj says, "It is certainly possible that Mercury, Venus, or Mars had similar impact events,” but this was outside the scope of the present study.

Bear in mind we don't know if the space debris model is correct; there is as much evidence against it as for it. It may have been a massive volcanic event that caused the end of the Dinosaurs - or a combination of things including the space rock and volcanoes and who knows what else.

As usual the author pretends we have more knowledge then we do.

And the article takes on a soothing tone in suggesting we know we won't get hit again. We know nothing of the sort. In fact, we have not really charted many near-Earth asteroids, much less the deeper space objects. We could get creamed any time. But such worry does nobody any good. Still, I don't like it when science writers blow smoke up our backsides.

Posted by: Timothy Birdnow at 11:49 AM | Comments (1) | Add Comment
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