hummer
06-27-2008, 02:25 PM
Washington, June 26: A giant crater made by an asteroid or comet explains why Mars is so lopsided, with a basin on one hemisphere and high terrain on the other, three separate teams of scientists said on late Wednesday.
The impact gouged out a hole 5,200 miles across and 6,500 miles long -- the size of the combined areas of Asia, Europe and Australia, the researchers reported in the journal Nature.
It would be the largest impact yet found in the solar system.
The three studies describe the true size of the depression, sometimes called the Borealis Basin. Some of the edges have been erased by volcanic activity, they said.
It appears to have held an ocean in the early days of the planet, before Mars lost so much of its atmosphere and the water either sublimated away or froze beneath the surface.
NASA's Phoenix Mars Lander last week scraped through the dry red dust covering the planet's surface to reveal what appears to be white ice underneath.
The impact gouged out a hole 5,200 miles across and 6,500 miles long -- the size of the combined areas of Asia, Europe and Australia, the researchers reported in the journal Nature.
It would be the largest impact yet found in the solar system.
The three studies describe the true size of the depression, sometimes called the Borealis Basin. Some of the edges have been erased by volcanic activity, they said.
It appears to have held an ocean in the early days of the planet, before Mars lost so much of its atmosphere and the water either sublimated away or froze beneath the surface.
NASA's Phoenix Mars Lander last week scraped through the dry red dust covering the planet's surface to reveal what appears to be white ice underneath.