Insightology

Asteroids are space objects and sometimes they hit earth. Depending on their size they can cause great damage. Small asteroids can burn up when they enter the atmosphere. Larger ones can hit earth and cause damage directly and indirectly. The most popular reason for the extinction of the dinosaurs 65 million years ago is asteroid strikes and the resulting global climactic changes. Okay, nothing new so far. Everyone can agree that asteroid strikes can have no to devastating impact. The next question is how likely are such impacts? To understand how frequently asteroids have struck earth in the past the traditional research method is to look for craters. Using this method scientists have estimated that large strikes happen about once in a million years or so. Then geophysicist Dallas Abbott began wondering if that kind of calculation made sense. Since about seventy percent of the earth is covered with water, wouldn't it make sense that most asteroid strikes are likely to have been in water than land. If so isn't it likely we have been underestimating the number of asteroid strikes on earth?

So, about a decade ago, she started looking for evidence underwater and has found quite a few. A particularly large one near Madagascar is estimated to have created a tsunami much bigger than the one from a few years ago near Indonesia. Currently, she is studying an impact crater near Australia that is estimated to have been created by an asteroid in 572 AD. An account of her work and questions that lead from it have been extensively explored in the June 2008 issue of the Atlantic Monthly  by Gregg Easterbrook.           

One of the biggest questions that comes out of this research is, what is the risk faced by the earth from an asteroid (or even comet) strike? Abbott's research idea leads one to think that it is much higher than before. But given the difficult (and expensive) nature of her work, it is not clear that even that kind of research can give a proper estimate of the risk faced by the earth.         

Dallas Abbott is Research Scientist and Intern Program Coordinator at Lamont-Doherty Earth Observatory in Columbia University. She is part of the Holocene Impact Working Group that studies issues related to submarine strikes. Their research is not sufficiently funded and they are likely to appreciate the benevolence of generous donors.