Imagine a place as cold as the South Pole in winter, drier than Chile's Atacama Desert, with air far thinner than at the summit of Mount Everest.
Add a pale sun, pink skies and an utter silence broken only by the whisper of a passing dust devil.
Welcome to Mars, the elusive target of a growing armada of spacecraft from Earth, and man's best hope for discovering, or perhaps pioneering, life beyond our home planet.
Tonight, Mars is at "opposition," which means observers on Earth stand briefly along a straight line drawn outward from the sun, through the Earth, to Mars. So, as the sun sets in the west this evening, Mars will be rising, as if on the opposite end of a celestial seesaw, in the southeast.
And on any clear night for the next month, you can go outside during the night and watch Mars make its way slowly across the southern sky, glowing like a smoldering red ember. There will be nothing brighter in the heavens except the moon.
Oppositions with Mars occur once every 26 months, when Earth, like a sprinter on an inside lane of its elliptical orbit around the sun, laps Mars as it loafs along an outside lane.
By June 21, Mars will be "only" 41.5 million miles from Earth - its closest (and therefore biggest and brightest) approach since 1988.
The next opposition, in August 2003, will be even more spectacular, bringing Mars within 34.5 million miles of Earth, and making it appear 25 percent bigger than this year. There has been no closer opposition for thousands of years, and won't be another so close until the 24th century.
Because oppositions bring Mars so near, they are the best times to hurl spacecraft toward the planet. The National Aeronautics and Space Administration has been launching Mars orbiters and landers in every opposition year since 1996 and, spurred by a debate over claims of fossil microbes found in meteorites from Mars, has similar plans through 2013.
This year's effort, NASA's $297 million Mars Odyssey spacecraft, was launched April 7. It's due to enter Mars' orbit Oct. 24, where it will map the planet's surface minerals, study its radiation environment and look for water.
That is, if all goes well. Both Mars missions launched by NASA for the 1998 opposition - Mars Climate Orbiter and Mars Polar lander - crashed or expired on Mars due to navigational or programming errors.
