Sep 8, 2003

The Planet that Won't Go Away

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The Planet that Won't
Go Away


Mars' closest approach to Earth was on August 27th--but the red planet is even easier to see now.




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September 8, 2003: "Tony, it's still there. I can't believe how bright it is!"


That's what my mother said to me on the phone last night. She had just stepped outside for some fresh air and was startled by an orange star hanging over her house: Mars--so intense it was worth a phone call.

Right: On Sept. 7th, Mars and the nearly-full Moon over Pittsburgh, PA. Credit: Jerry Xiaojin Zhu.

Like millions of other people, she saw Mars for the first time on August 27th when the red planet made its closest approach to Earth in 60,000 years. It was dazzling, but ... "isn't Mars supposed to be gone now?"

No, Mom. In fact, Mars is even easier to see now than it was two weeks ago.




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Consider this: Mars is receding from Earth at about 6,000 mph (2.8 km/s). Maybe that sounds fast, but on the vast scale of the solar system it is not. Mars was 34,647,397 miles from Earth on August 27th. Today it is 35,532,907 miles away--not much different.

That's why Mars remains dazzling. It's still nearby. In fact, during the whole month of September Mars will be as close to Earth as it's going to get for the next 15 years.

Best of all, Mars getting easier to see. Why? Because it's up before bedtime. Like all stars and planets Mars rises about 4 minutes earlier each night. (This is a result of Earth's orbital motion around the sun.) Back on August 27th, Mars was barely above the horizon at sunset; you had to wait a while for it to rise. Now, though, Mars is higher in the sky when the sun goes down. People are noticing the red planet without even trying.


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Above: After sunset on Monday, Sept. 8th, look for Mars and the Moon rising in the southeast. The pair will be even closer together before sunrise on Tuesday, Sept. 9th. [sky maps:

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Eventually, of course, Mars is going to fade. By late September it will be only half as bright as it is now, and by mid-October only 20%. The fading quickens because Mars is receding a little faster each day. Only 6,000 mph now, the pace will increase nearly 3-fold to 16,500 mph (7.4 km/s) by the end of this month.

All these factors add up to one thing: September is a good time to observe Mars.


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Even a modest backyard telescope, a 6- to 8-inch instrument, say, will reveal broad details on the planet's surface such as dark volcanic terrains and the bright south polar cap. Larger 12- to 16-inch telescopes equipped with CCD cameras can record spectacular images of individual volcanoes, wispy clouds and frosty mountains emerging near the south pole.

Right: Astrophotographer Donald Parker of Coral Gables, Florida, took this picture of Mars on Sept. 3rd using a 16-inch telescope and a CCD camera. South is up.

Or if you're like my mom, not ready to deal with telescopes, just use your naked eye. The planet that won't go away is a lovely sight no matter how you look at it.



Editor's notes: (1) The author thanks Dr. Clay Sherrod for pointing out that, compared to Sept. 2003, Mars won't be as close again until 2018. (2) In the story's first image, note the rainbow-splash of light between the Moon and Mars. That's a moondog.


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Beware of dust storms: September marks the beginning of dust storm season on Mars, for two reasons: (1) Mars reached perihelion, the part of its orbit closest to the Sun, on August 30th and (2) summer will begin in the southern hemisphere of Mars on Sept. 29th. Sun-warmed summer air moving across the arid martian landscape tends to pick up dust, forming clouds big enough to see through backyard telescopes. These clouds are fun to watch--unless they grow out of control and encircle the entire planet. When that last happened in 2001 astronomers couldn't see the surface of Mars for months.

Mars Falls (below): French photographer Vincent Vilela took this picture of Mars over Niagara Falls on Sept. 7th. The view is from Canada looking toward the United States. Copyright Vincent Vilela, all rights reserved.


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Close Encounters with Mars -- (Science@NASA) Everyone on Earth was close to Mars on August 27th--but who was closest? Read this story to find out.

Mars Dust -- (Science@NASA) Using only backyard telescopes, amateur astronomers are enjoying great views of dust clouds on Mars

Mars is Melting -- (Science@NASA) The south polar ice cap of Mars is receding, revealing frosty mountains, rifts and curious dark spots.

Missions to Mars: NASA is sending a pair of robotic rovers to Mars. Named Spirit and Opportunity, they are due to land in 2004. Find out more about them from the Mars Exploration Program home page.

Making a Splash on Mars -- (Science@NASA) On a planet that's colder than Antarctica and where water boils at ten degrees above freezing, how could liquid water ever exist? Scientists say a dash of salt might help.

Once Upon a Water Planet -- (Science@NASA) Today the Red Planet is dry and barren, but what about tomorrow? New data suggest that the long story of water on Mars isn't over yet.

Images of Mars from the Association of Lunar and Planetary Observers (ALPO)


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