Signs of huge Antarctic meteorite impact found
Artist's rendition of a colossal meteorite that scientists at Ohio State University think struck the Earth over 250 million years ago. Using gravity measurements from NASA's GRACE satellites along with aerial radar, scientists have detected signs of what might be a 300 mile wide impact crater buried under a mile of Anatarctic ice. More images below.
JB: I’m Joel Block.
DB: And I’m Deborah Byrd for Earth & Sky. Scientists have found the first evidence of what they think is an enormous impact crater in Antarctica.
JB: The research team was led by geophysicist Ralph von Frese of Ohio State University. Von Frese examined data from a satellite that mapped subtle differences in Earth’s gravitational field. He found a large area in Antarctica of unusually dense rock. Radar images from aircraft revealed a large basin, which von Frese thinks is an impact crater 500 kilometers, or about 300 miles wide.
Ralph von Frese: For impact craters, there’s a sort of Mexican hat, or sombrero anomaly in the gravity field that is quite recognizable when you see it. And it’s complimented by a crater.
DB: A meteorite strike this large would have wreaked havoc for life on Earth. Von Frese thinks it might be associated with the Permian-Triassic extinction, which is thought to have extinguished 95% of all life on Earth, about 250 million years ago.
Ralph von Frese: People have started looking at meteorite impacts as a possible agent for these extinctions.
JB: But scientists haven’t yet collected an actual piece of the giant meteorite, which would be buried beneath more than a kilometer of ice. More at earthsky.org. Thanks today to NASA. We’re Block and Byrd for Earth & Sky.
Our thanks to:
Ralph von Frese
Professor
Department of Geological Studies
Ohio State University
Columbus, Ohio
Additional Teacher Resources
NASA: Evidence for a Large Impact at the Permian-Triassic Boundary
A NASA news conference was held May 13 to announce the discovery of an impact crater near Australia that might be implicated in the greatest mass extinction of all time— the Permian-Triassic or PT event, 251 million years ago.
NASA: Impact Craters
Craters are bowl shaped depressions made when a meteorite collides with a planet or moon. Good examples of craters can been seen on the surface of the Moon. Early in the history of the solar system, after the formation of the planets and their moons, there was still a lot of smaller objects in inter-planetary space. Over time many of these objects collided with the earth and moon. Because the moon has no atmosphere and is not geologically active, the craters are still visible. On earth, however, the workings of the atmosphere, water, and continental movements have hidden most craters. Over 150 impacts have been studied on the earth, though the true number will never be known.
