November 08, 2005
Tuesday

Dan Overcash encourages people to go outdoors in the next few weeks, look at Mars in the night sky and dream about whether Martians exist.

The University of South Carolina astronomy instructor said Mars would be very visible in the night sky for about the coming month.

"Nobody expects Mars to be that bright," he said.

Earth is as close to the Red Planet as it will be again until 2018, Overcash said. Earth is now about half an astronomical unit away from Mars, he said. An astronomical unit measures about 150 million kilometers.

Mars was about one-third of an astronomical unit away from Earth in 2003, Overcash said. But Mars wasn't as high in the sky then and wasn't as clearly visible from Earth, which is the larger and warmer of the two planets, he said.

On a clear night, a person using a telescope might be able at times in the coming month to see the southern polar cap of Mars or a dust storm on the Martian surface, he said.

Mars has seasons, as Earth does, Overcash said. So people have been intrigued by the thought of life on Mars.

"People want to believe in Martians," he said.

Many people can recall science-fiction accounts of Martians coming to help solve problems on Earth or Martians using truth serums on humans, he said.

Harry McSween, a co-investigator in the Mars Exploration Rover mission being conducted by NASA, said the rovers have shown evidence of the past existence of water on Mars.

"This was water that was there billions of year ago," said McSween, who is a professor of Earth and planetary sciences at the University of Tennessee.

Scientists are interested in evidence about water because life "as we know it or can imagine it" requires water, McSween said.

One of the two rovers is now about to start taking images of a crater on the Martian surface, he said. "It's a very photogenic place," he said.