Moon, Mars, and Gemini

StarDate: October 10, 2009

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As the days get shorter and cooler, many parts of the country will soon be seeing dustings of the white stuff. But Earth isn't the only planet where it snows -- it dusts the surface of Mars, too.

Mars is a cold, barren world. Its thin, dry atmosphere does little to warm the planet. Yet there is a little bit of water vapor in the atmosphere. It forms thin clouds high in the sky.

Until last year, scientists weren't sure whether those clouds produce any snowfall -- and if they do, whether it reaches the ground. But the Phoenix lander showed that snow does fall on the orange landscape.

Phoenix landed in the high northern plains, not far from the edge of the winter ice cap. It operated for five months, until the Sun dropped too low in the sky to charge its solar-powered batteries.

One of Phoenix's instruments detected snow falling from the clouds above it. Because it was summer, the snow didn't hit the ground. But mission scientists say that during the winter, it should coat the surface with a fresh blanket of white.

Mars is in good view late tonight. It rises in the wee hours of the morning, to the lower left of the Moon, and is high in the sky at first light. Mars looks like a bright orange star. Two true stars are nearby -- Pollux and Castor, the "twins" of Gemini. They're to the left of the Moon, forming a fairly even line with Mars.

We'll have much more about this bright morning lineup tomorrow.

Script by Damond Benningfield, Copyright 2009

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