Close Encounter With Mars

Night after night, the red beacon shining in the southern sky has been growing brighter. Residents of even light-polluted metropolises, whose experience with celestial lights is usually limited to the moon, Venus and airplanes, will get their best view yet of the planet Mars. That's because on Wednesday, Aug. 27, the Red Planet will approach to within about 34,600,000 miles of Earth. It hasn't come that close--and thus hasn't been as bright--for almost 60,000 years, the better part of human history. And if you happen to miss that historic night, don't worry: you can still get a superb view over the next few weeks.

The close encounter has spurred observatories and astronomy clubs to throw "star parties" in Portland, Ore., and Portland, Maine; in Winnipeg, Man.; in Austin, Texas; and in Singapore, Vienna and hundreds of other places around the world. Experienced observers will let the uninitiated peer through telescopes and binoculars for a glimpse of this heavenly show. "My phone hasn't stopped ringing," says Derrick Pitts, chief astronomer at Philadelphia's Franklin Institute science museum and host of a show on the Mars encounter that will be broadcast over many PBS stations this week.

If they are lucky, novices may actually see one of Mars' ice caps or its broad, bright plains, but conditions would have to be perfect. Even without a telescope or a guide, there will be no mistaking the brilliant red starlike object that rises in the east just as the sun is setting and continues to climb higher throughout the evening. With Venus currently hidden by the sun's glare, only the moon will outshine Mars.

There's no need to persuade people that it's worth a look. The Red Planet has fired the human imagination ever since Italian astronomer Giovanni Schiaparelli thought he saw artificial canals on its surface in 1877. (The canals were debunked as an illusion in the early 1900s.)

Hope that there is life on Mars revived over the past decade, when detailed photos revealed that the surface appears to have been carved by flowing water; liquid water is necessary for life as we know it. And while few scientists now support the 1996 claim that fossil microbes had been found in a Martian meteorite, most remain convinced that Mars might have harbored life in the distant past--and that some micro-organisms could still be hanging on beneath the frozen surface. The search for subsurface water and for those microscopic holdouts is the focus of several probes on the way to Mars and others to be launched over the next decade.

For scientists, that's where the excitement lies, not in this week's approach. The two planets come close every 26 months or so, as the closer-in, faster-moving Earth laps the slower Mars on their journeys around the sun. But Mars' orbit isn't quite circular; it's elliptical, so it's sometimes closer to and sometimes farther from the sun. (Earth's orbit is also elliptical but much less so.) When the Earth catches up at a time when Mars is relatively near the sun, there's an especially close encounter. In 1988 the planets were just a few tens of thousands of miles farther apart than they are now. The year 2287 will break this year's record; they will be 40,000 miles closer.