Reported July 2009

WALKING ROCKS: Rocks on an area of Mars were found in strangely orderly patterns. Scientists found that the rocks moved into these patterns by rolling into the wind. When the wind blows, it picks up sand in front of the rocks and pulls it away, leaving a small cavity. As the wind continues to blow, it pulls enough sand from under the rock that it rolls forward into the hole due to gravity. As the rocks move, they can block the wind from other rocks, which leaves wind rushing past the side of a rock, where it can create a hole and cause a rock to migrate laterally, helping to form a regular pattern that is repeated around Mars.

WIND ON EARTH: Wind is a form of solar energy, caused by the uneven warming of the earth's surface. This is why air masses have different temperatures and pressures, and are constantly moving to find a balance. The higher the difference in pressure, the swifter the air moves and the stronger the wind. Mankind has used wind energy for thousands of years, using it to pump water, grind flour, press olives, and even to explore the world in wind-driven sailing ships.

The American Geophysical Union contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Jon D. Pelletier
Tucson, Arizona
(520) 626-2126
jdpellet@email.arizona.edu

Peter Weiss
American Geophysical Union
Washington, DC 20009-1277
(800) 966-2481
http://www.agu.org
pweiss@agu.org

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