Moon and Planets

StarDate: June 18, 2009

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A beautiful solar-system lineup will greet early risers tomorrow: the Moon and the planets Venus and Mars. Venus is the "morning star" to the lower right of the Moon. Mars is roughly between them, a little closer to Venus.

Although Mars isn't nearly as bright as Venus, it's still a pretty sight, particularly because of its orange color.

If you were standing on Mars, orange is about the only color you'd see. Much of the Martian surface is coated by a fine orange dust. There are no blue oceans on Mars, no green plants. And there's no blue sky, either -- winds carry dust high into the sky, coloring it orange, too.

The winds are both a curse and a blessing for the craft that land on Mars. So far, Martian landers and rovers have all used solar power, so they have panels of solar cells that convert sunlight to electricity.

The problem is, dust piles up on top of the panels, reducing the amount of power they produce. The problem is especially bad when the wind stirs up giant dust storms. The storms not only pile a lot of dust on the solar panels, they darken the skies, too. Late last year, the combination of dust in the air and on its solar panels left the Spirit rover with barely enough power to survive.

But the winds can also clean off the solar panels -- especially the little twisters known as dust devils. Spirit got a couple of cleanoffs early this year. That gave it extra power to keep studying the orange landscape and skies of Mars.

Script by Damond Benningfield, Copyright 2009

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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