First comet dust on Earth’s surface found in Antarctic ice

Science : Dust from comets is hard to come by. It is either collected high in Earth’s atmosphere or by spacecraft sent through the trails of comets. Takaaki Noguchi of Kyushu University in Fukuoka, Japan, and his colleagues began collecting Antarctic ice in 2000, melted the ice, and filtered the particulate matter out of the water. They found 3000 micrometeorites 10 μm or larger, which they examined under a microscope individually over a period of five years. Just over 40 of the particles were revealed to be identical to comet dust found in the stratosphere. Cometary material has been found in Antarctica previously, but in this most recent collection the dust is fragile and porous and was expected to be burned up passing through Earth’s atmosphere. The dust found is more common and much cleaner than that collected by planes, so it is a better subject for study.