Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



Evidence That Asteroids Change Color As They Age

This enhanced false color image of Ida with its small satellite Dactyl to the right gives a vivid example of the effect of space weathering on asteroids. Blue regions on the asteroid tend to be associated with fresh young craters where subsurface material has been recently exposed to space. There are also blue regions associated with ridges and steep hills where surface material falls down during small "asteroid-quakes" to expose fresh surfaces. Red regions on the surface correspond to old craters and flat surfaces that have not been disturbed in a very long time. By measuring the rate of space weathering on asteroids Jedicke and his collaborators can now estimate the ages of the various colored regions on the surface of asteroids like Ida. Photo courtesy of NASA/JPL
Honolulu (SPX) May 19, 2004
In an article published this week 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."

Nesvorny explains that this is similar to the situation experienced by asteroid astronomers. "The meteorites are gifts of the solar system to scientists on Earth--pieces of asteroids delivered to their own backyard. The mystery is that the OC meteorites have a bluish color relative to the reddish color of the asteroids from which they were supposedly released." Jedicke asks, "How could they possibly be related?"

About thirty years ago, a "space weathering" effect was proposed to explain the color change. Meteorites, whose surface is affected by their fall through Earth's atmosphere, are usually studied in laboratories by observing their freshly cut and exposed interiors. Billions of years of exposure of the same material on the surface of an asteroid to solar and cosmic radiation and the heating effect of impacts of tiny asteroids might alter the surface color of asteroids in exactly the manner required to match the color of asteroids.

Jedicke said that they found that "asteroids get more red with time in exactly the right manner and at the right rate to explain the mystery of the color difference between them and OC meteorites." He added, "Even though we have found a link between the two types of objects, we still don't know what causes space weathering."

Once these researchers refine their analysis by obtaining more colors of the youngest-known asteroid surfaces, it will be possible to determine the age of any asteroid from its surface color. They are currently searching for a space weathering effect on other types of asteroids in the solar system.

Related Links
Nature
Institute for Astronomy at the University of Hawaii
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

The Rough Shape Of Asteroid "ITOKAWA" Revealed
Tokyo - Apr 27, 2004
A recent radar observation clarified the rough shape of an asteroid called "ITOKAWA", where the MUSES-C (Hayabusa) is heading for. A research group led by Dr. Steve Ostro of the NASA Jet Propulsion Laboratory carried out observations by transmitting radio waves to ITOKAWA from the radiotelescope at the Arecibo Observatory in Puerto Rico.



Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only






Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News








The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.