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Eyes On The Sky

By Brenda Iasevoli

Every million years or so, an asteroid tears through Earth's atmosphere and smacks right into the planet. It is David Morrison's job to protect the planet from such a collision. He is an asteroid hunter.

Asteroids are rocky objects that orbit the Sun. Most of them are found in a region between the orbits of Mars and Jupiter. They can be as tiny as a speck of dust or as big as a mountain. Sometimes, an asteroid's orbit brings it close to Earth. Scientists believe that an asteroid wiped out the dinosaurs nearly 65 million years ago.

"The Earth is in a kind of celestial shooting gallery," says Morrison, who is the senior scientist at the NASA Astrobiology Institute, in Mountain View, California. "We've been hit by millions of asteroids, and we will be hit again," he told TFK. "It could be tomorrow, or it could be a million years from now."

Morrison and his fellow hunters use special telescopes to search for and track asteroids. Their goal is to discover the most dangerous ones--those that are more than a half mile in diameter--within the next 10 years. There are about 1,100 such asteroids. As-tronomers have their eyes on almost 65% of these.

For asteroid hunters, the danger of an asteroid aimed at Earth is not the stuff of science fiction. In June of 2002, one the size of a football field missed Earth by just 75,000 miles. It was the closest near collision ever recorded.

But earthlings can take heart. Scientists know to watch for asteroids now, and Morrison is confident that we will soon have the technology to deflect earthbound objects before they strike. "Asteroid hunting is a different kind of astronomy that involves protecting the Earth," he says. "Astronomers can save the world."

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