Mars putting on big show for stargazers

June 13, 2001
Web posted at: 11:13 a.m. EDT (1513 GMT)

larger   A composite image of Mars created with images snapped by the Mars Global Surveyor. The picture is a composite of color strips taken on nine successive orbits from pole-to-pole over the planet in March 1999. The color in this picture is computer-enhanced and is not as it would appear to the human eye

(CNN) -- Mars is ready for its close-up. On June 21, Earth and Mars will be about 42 million miles (67.3 million kilometers) apart, the closest the two planets have been since 1988 when they came within 37 million miles (59 million kilometers) of each other.

As Earth races toward the red planet at 22,000 mph, Mars appears as a brilliant orange disk, brighter than any other object in its region of the sky -- except on nights when the moon is nearby.

On June 13, Mars reached "opposition," the moment when the Sun, Earth, and Mars formed a straight line. When a planet reaches opposition, it lies exactly "opposite" the Sun in the sky.

Because both Earth and Mars follow elliptical orbits around the Sun, with the orbit of Mars more oval than Earth's, Mars makes its closest approach to Earth this year several days after opposition.

Later in the summer Mars will fade, but will remain the brightest "star" in the evening sky until October.

Mars is easy to spot because of its striking reddish color. And while the planet is bright in the sky, it doesn't twinkle like a star.

Mars Fact Box Diameter: 4222 miles Length of day: 24.7 (hours) Average distance from sun: 141.6 million miles Surface composition: Basaltic rock; altered materials Average surface temperature: -85 degrees F Number of moons: 2 Ring system: No Global magnetic field? No Source: NASA   ALSO Depth Specials     MESSAGE BOARD Stargazing

As the space narrows between Earth and Mars, astronomers say even sky-watchers using small, 4 to 6 inch telescopes may be able to make out some features on Mars, including clouds, surface markings and polar caps.

The Mars viewing gets even better in coming years.

On August 27, 2003, Earth will swing to within 34.6 million miles (55.7 million kilometers) of Mars. Astronomers say that on that date, the Earth-Mars distance will be the smallest it has been in at least 5,000 years.

Meanwhile, NASA's newest Mars probe, 2001 Mars Odyssey, will soon provide a different angle on the red planet.

Odyssey blasted off April 7 and will enter Mars orbit on October 24. During the probe's two and a half year mission, it will monitor space radiation, seek out underground water, and identify interesting minerals on the martian terrain.

Another NASA probe already is circling Mars. Launched on November 7, 1996, Mars Global Surveyor started its mapping mission on April 1, 1999 and has sent back tens of thousands of pictures.