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Dr.
Eleanor Helin of NASA's Jet Propulsion Laboratories explains her
work as Principal Investigator of the
Near-Earth
Asteroid Tracking
(NEAT) program, which keeps a watch on bodies
in space that may present a future threat to life on earth.
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y
early October, backyard astronomers are picking up the approaching
asteroid with their telescopes. The mile-wide chunk of space
rock is on a collision course with the earth. On October 26,
it's the brightest object in the sky, save for the moon. Traveling
at nine miles per second, the asteroid enters the earth's atmosphere
on October 28. Friction from the atmosphere heats the surface
of the object to more than 3,000 degrees Fahrenheit. As the
object sails through the atmosphere, it produces a streak of
light that we call a meteor or "shooting star." About
ninety miles above the earth, the extreme heat melts the meteor's
hard shell and it bursts into a crackling, hissing fireball.
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From
1977 until 2003, the Exploratorium published a quarterly magazine.
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