The Sciences

Sky Lights

Who needs a telescope when the Red Planet is this close?

By Bob BermanMay 1, 1999 5:00 AM


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by Bob Berman

Sky fashions come and go, but affection for Mars never wanes. Even as recent discoveries of deep-space sparklers like quasars, novas, and exploding galaxies shift attention from planetary gazing, the Red Planet stubbornly refuses the status of a has-been.

This view of Mars was made from Voyager images. The polar caps, craters, volcanoes, and plains are easily seen with a good telescope. But even with the naked eye, Mars is dazzling this month.USGS/SPL/Photo Researchers

Instead, Mars amazes with new discoveries: fluvial channels cut by ancient rivers, surface soils brimming with oxygen, and fossils of what may be microscopic life, found on a blown-off chunk of Mars that crashed into Antarctica 13,000 years ago. Mars, with its fantastic sky (sometimes pink, sometimes cobalt blue) and chocolate-colored deserts, never fails to intrigue. Beginners often assume that capturing Martian detail is as easy as buying a good telescope, but there are other important considerations, such as choosing the right time to observe the planet. This month is ideal because Mars will dominate the midnight sky, offering backyard viewers a rare opportunity to acquaint themselves with the surprising planet.

We aren't usually so lucky. That's because Mars, of all the planets, displays the largest proportional variation in distance of any planet, forever playing peekaboo with us. When Mars is at the far side of its orbit, it's six times more distant, six times smaller-looking, and nearly a hundred times fainter than when nearest Earth. At the far point, it appears no larger than Uranus, just a tiny featureless blob. But when it comes near, Mars lights up the sky.To see for yourself, simply face south, ideally after 11 P.M. Halfway up the sky floats a single orange light, the brightest in the heavens. That's Mars. You don't need charts, and you don't need to know the constellations. Finding Mars is as easy as spotting the World Trade Center from a 737 flying over Manhattan. (But if you'd feel more comfortable with a sky steward to guide the way, use the moon, which hovers near Mars on April 29 and May 25.)

Mars has not swung this close to us for nine years, and this is only the beginning of good Mars gazing. In 2001 and 2003, the encounters will be even closer. The 2003 meeting will be spectacular, with Mars reaching its closest approach to Earth in a century. It will then look 50 percent larger than it does now and somewhat lower in the sky. Although in 2001 Mars will be closer to us than now, our Northern Hemisphere will be maximally tipped away from the Red Planet; our telescopic views of Mars, which will lurk even lower than the December sun, will be blurred by the amount of atmosphere we must peer through at the horizon.

Even now the Northern Hemisphere tilts slightly away from Mars, and only those living 11 degrees below the equator can spy it straight up in the sky. Still, the planet won't be this high in our sky again during any close approach until 2005. So this month will provide the best viewing for years to come.Mars will fly closest to Earth on May 1 but will remain well positioned all month, floating colorfully near Spica, Virgo's blue star. Dazzling Venus, which sinks into the fading northwestern twilight just as Mars ascends in the southeast, will hang balanced on the opposite side of the heavens. The opposing positions of our two neighboring planets symbolize vastly different natures: one offering vivid, tinted, frozen detail easily seen in a telescope, and the other a broiling, dazzling white sterility no optical device can penetrate. What a choice--a planet for any mood.

Galactic Sky Charts -- maps and planet finder for various latitudesDeepsky Atlas -- maps and information from the Hawaiian Astronomical SocietyBasic Celestial Phenomena website"What's Up in the Sky" from Sky Publishing

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