Starwatch: Mars will be close this month

  • Fri Jan 22nd, 2010 3:21pm
  • Life

By Mike Lynch

Every summer there’s misleading e-mail that circulating about how on Aug. 27 Mars will be as close as it’s been to Earth in 60,000 years and will be as big as a full moon.

Some folks have fallen for it, grabbing lawn chairs, mosquito juice and over inflated high hopes to see this momentous event, and … nothing happens. Just another pleasant evening under the stars.

The annual Mars hoax is based on a real event that did take place on Aug. 27, 2003, when Mars was the closest it’s been to Earth in 60,000 years. It was a great event, but by no means was Mars as big as a full moon, not even close.

This month Mars will be the closest it’s been in more than two years. Astronomers call it opposition, and it happens when the Earth and another planet are lined up with the sun, with the Earth in between the sun and the planet.

This only happens to a planet like Mars that is farther away from the sun than Earth. As you can see in the diagram, that geometrically puts the sun and Mars at their minimum distance. This set up occurs every 780 days, a little over two years. The actual date of opposition this time with Mars is Jan. 27 when the Red Planet will be 61.6 million miles away.

Not all oppositions are alike, especially in the case of Mars, because Mars’ orbit is slightly oval. As it orbits the sun every 687 days, Mars reaches perihelion, or it’s closest point to the sun, about 128 million miles, and aphelion, or it’s farthest point away, at nearly 157 million miles.

This eccentricity of Mars’ orbit is affected by the gravitational influence of other planets, especially the very massive Jupiter.

This time around Mars is nearly at apehelion with the sun during opposition, and that puts the distance between Earth and Mars a little greater than average. So this opposition with Mars won’t be all that great.

In August 2003 Mars and Earth were only separated by 34.3 million miles. This time around Mars will be nearly 62 million miles at opposition. The next really close opposition of Mars will take place in 2018 when the Red Planet will be just under 36 million miles from our backyards.

Finding Mars in the evening sky is easy. Just look for the brightest starlike object you can see in the low eastern sky. It has a copper-red tinge to it. Even with a telescope you’re not going to see much detail.

You may a small reddish disk, and if conditions are just right, you might see a little patch of white on the upper limb of the disk. If your telescope gives you an upside down inverted view, like most do, what you can see of the polar cap will be on the lower limb of the disk.

It’s also a good idea to wait until Mars is higher in the sky to view with your telescope, after about 10 p.m.

Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, “Washington Starwatch,” available at bookstores and at his Web site

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