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Moon and Mars

September 22, 2011

The Moon and the planet Mars highlight the pre-dawn sky tomorrow. Mars looks like a bright orange star a little to the upper left of the Moon. They’re well up in the east at first light.

Mars has a couple of moons of its own, although they look nothing like our Moon. They’re much smaller, and they’re lumpy.

Phobos, the closer of the two, looks only about a third as wide as the Moon does from Earth. It moves around Mars so quickly that it rises in the west and sets in the east. And from the planet’s polar regions, it never climbs into view at all.

Deimos is visible from the entire planet, but it’s too small to see any detail on its surface. Instead, it looks like a brilliant star. It moves across the sky slowly, so it stays in view for more than two-and-a-half days, then disappears for the same amount of time.

Those aren’t the only differences you’d see in Mars’s night sky.

Because the planet’s atmosphere is less than one percent as thick as Earth’s, the stars wouldn’t twinkle as much as they do in our own sky. And the light of the small moons wouldn’t create as much glare as our moon does, so you could view faint stars even when both moons were in the sky. You wouldn’t have the pesky glow of artificial lights, either, leaving dark skies all the time.

And a bright double “star” would sometimes highlight the sky before sunrise or after sunset, one shining bright blue, the other white and much fainter: Earth and the Moon.


Script by Damond Benningfield, Copyright 2011


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