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The heat generated from the mess left by craters may help identify their age, at least on the planet Mars, reports the Independent. In infrared images of the martian surface obtained by the THEMIS instrument on the NASA Odyssey spacecraft show that craters are surrounded by dark haloes in daytime images and bright haloes at night. Since infrared is all about seeing in heat, the THEMIS images reveal that the debris around the craters, which was ejected during impacts, is hotter than its surroundings during the night and colder during the day. The reason for the difference in temperature is thought to be due to the large size of boulders in the ejecta since these will heat up in the sun in the morning and cool down at night much more slowly than surfaces covered with sand. The haloes become less distinct around older craters since boulders become smaller as they are worn away by erosion. Dr Philip Christensen, the chief scientist of the THEMIS team, believes that the intensity of the haloes surrounding craters could be used to identify their age if the rate at which boulders breakdown could be calculated. If the age of individual craters could be estimated from the THEMIS data it would allow the age of features on Mars to be dated much more accurately than ever before.
More info: The Independent
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