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Mars in Conjunction

February 3, 2011

Mars is hiding in the light. Tomorrow, the little planet will pass behind the Sun as seen from Earth, so it's immersed in the Sun's glare. It'll return to view in late spring, but it won't be in good view until summer.

Because Mars is the next planet out from the Sun, it takes longer for it to orbit the Sun than Earth does -- about 22-and-a-half months.

But while Mars is going around the Sun, so is Earth. The combination of motions means that, on average, Mars comes to the same point in our sky relative to the Sun every 25-and-a-half months. So Mars will next pass behind the Sun -- a point known as conjunction -- in the spring of 2013.

Over the coming year, Mars will move away from the Sun in our sky. At first, the motion will be slow, in part because Mars is a long way away -- more than 200 million miles right now. Later, though, as Earth begins to catch up to Mars in our smaller, faster orbit around the Sun, the planet's motion across the sky will accelerate. It'll move farther from the Sun each day until it reaches opposition, when it lines up opposite the Sun. That's when Mars will look its best -- it'll shine like a bright orange beacon all night long.

That won't happen until March of next year, though. For now, all we can do is wait for Mars to start to emerge from the light of the Sun's glare and begin its slow climb across the night sky.

Tomorrow: wiggles, jiggles, and bumps on the Moon.


Script by Damond Benningfield, Copyright 2010


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