Moon and Mars

StarDate: July 15, 2010

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You never know what the winds are going to do at this time of year. High pressure across parts of the country can tamp the wind down completely. At the other extreme, thunderstorms and hurricanes can stir up winds that are strong enough to demolish buildings.

Winds blow on most of the other planets of the solar system, too, including Mars, which is in good view this evening. It's to the upper right of the Moon, and looks like a bright orange star.

As with Earth, the winds on Mars vary by quite a bit. At times, they're calm -- there's no breeze at all to stir up the planet's orange dust. And at other times, they're a gale, not only stirring up the dust, but spreading it around the planet.

The strongest sustained winds on Mars blow when winter gives way to spring in both northern and southern hemispheres. Frozen gases in the polar ice caps vaporize and rush into the atmosphere, creating strong winds. These winds easily pick up the powdery dust at the surface and carry it high into the sky, creating dust storms. The storms can cover tens of thousands of square miles. And the most extreme storms can cover the entire planet, cloaking Mars in an orange veil for weeks or even months.

Local winds can get pretty gusty, too, stirring up small columns of dust known as dust devils. They can reach more than a mile high, and scoot dozens of miles across the landscape -- carried by the winds of Mars.

Script by Damond Benningfield, Copyright 2010

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