New theory on the two faces of Mars: gigantic collision

David Perlman, Chronicle Science Editor
Wednesday, June 25, 2008


(06-25) 16:04 PDT SANTA CRUZ -- It must have been the biggest blast in the history of our solar system - the impact of a planetary bomb as powerful as a billion billion tons of TNT that scarred Mars nearly 4 billion years ago.

And if the theories are right, it blasted out the biggest crater that any planet has ever survived.

It was a convulsion far bigger than the puny one that drove the dinosaurs to extinction on Earth only 65 million years ago, and likely bigger than the crashing object that some have theorized gouged out our own moon from the young Earth's surface and sent it flying into orbit. Now three teams of astronomers are proposing that Mars once survived the impact of some giant object from space that divided the entire planet's surface into two totally distinct regions:

One region of the surface is the huge oval-shaped scar of the impact itself, covering more than a third of the Martian surface and including all the vast low-lying lands of the planet's far north where the Phoenix spacecraft is now digging up buried nuggets of ice.

The other is the even larger highland region to the south, marked by deep canyons, high mountains and the remains of giant volcanoes.

more:http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/06/25/BA3P11EVOM.DTL

...in the 90s.

Fascinating piece. Thanks. :thumbsup:

OK, big collisions. But I don't think it was bigger than ours.

Cool article, though. Thanks.