No, this is not Mars, though it looks about as hospitable. It's the Moroccan desert. It's also the site of an apparent visit from space. At this location scientists recently found evidence for an ancient impact by a space rock.

Look to the background at the far right. There is a saddle-shaped dip in the weathered buttes. There, scienists led by Brooks Ellwood of Louisiana State University found signatures in the soil of an impact the researchers think led to a mass extinction of aquatic species [SPACE.com Astronotes, June 13, 2003].

There's nothing obvious left from the event, which occurred 380 million years ago. No crater, or anything like that. Earth hides ancient evidence by folding it into the planet and weathering whatever is exposed. The Moon, on the other hand, maintains a record of similar collisions. Its pockmarked face looks about like Earth's would if things here didn't change so much through time.

Ellwood said the evidence his team found is not conclusive.

"Weathering, upheavals, volcanos, earthquakes and flooding all confuse the geologic record, making it incomplete and open to interpretation," he said. Ellwood and other experts agree on one thing: Another big rock will shake Earth again someday.

"We could protect ourselves if we wanted," he said. "We went to the Moon, we can figure out how to destroy or deflect a meteor. All it takes is the political will -- and an awareness of the threat."

Or maybe we could just move to Mars.

-- Robert Roy Britt