May 19, 2004 by Robert Jedicke @ Institute for Astronomy, Hawaii
In an article published today in the journal Nature, a team led by Robert Jedicke of the University of Hawaii’s Institute for Astronomy provides convincing evidence that asteroids change color as they age.
David Nesvorny, a team member from the Southwest Research Institute in Boulder, CO, used a variety of methods to estimate asteroid ages that range from 6 million up to 3 billion years. Accurate color measurements for over 100,000 asteroids were obtained by the Sloan Digital Sky Survey (SDSS), and catalogued by team members Zeljko Ivezic from the University of Washington and Mario Juric from Princeton University.
Robert Whiteley, a team member from the USAF Space and Missile Systems Center in Los Angeles, points out that “the age-color correlation we found explains a long-standing discrepancy between the colors of the most numerous meteorites known as ordinary chondrites (OC) and their presumed asteroid progenitors.” Meteorites are chips of asteroids and comets that have fallen to Earth’s surface.
According to Jedicke, “If you were given a piece of rock from the Grand Canyon, you might expect that it would be red, like the colorful pictures in travel magazines. You’d be forgiven for questioning its origin if the rock had a bluish color. But if you were then told that the rocks turn from blue to Grand Canyon red because of the effects of weather, then everything might make sense. Your gift is simply a fresh piece of exposed rock, whereas the pictures you’ve seen show weathered cliff faces millions of years old.”
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