Just passing by.A giant space rock is headed our way. Is Earth doomed, or is the threat of impact just a false alarm? On September 29, a city-size asteroid (space rock that revolves around the sun and is smaller than a planet) named Toutatis (too-TAH-tiss) will pass within 1 million miles of Earth. That's only four times farther than the moon--a close shave shave (shav) 1. to cut at or parallel to the surface of the skin. 2. to remove the beard or other body hair by such a process. 3. to cut thin slices from or to cut into thin slices. by space standards. But according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. astronomers Famous astronomers and astrophysicists include: Directory: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
NASA in full National Aeronautics and Space Administration Independent U.S. scientists use telescopes to track "Near-Earth Asteroids Near-Earth asteroids (NEAs) are asteroids whose orbits are close to Earth's orbit. Some NEAs' orbits intersect Earth's so they pose a collision danger. On the other hand, NEAs are most easily accessible for spacecraft from Earth; in fact, some can be reached with much less fuel (NEAs)," or asteroids This is a list of numbered minor planets, nearly all of them asteroids, in sequential order. As of late September 2007 there are 164,612 numbered minor planets, and many more not yet numbered. Most asteroids are ordinary and not particularly noteworthy. that cross Earth's orbit (path around the sun). "We know their trajectories [paths] well into the future," says Steven Ostro, a NASA astronomer. Although Earth is safe from Toutatis for now, the future forecast isn't as bright. The tug of gravity (force that pulls two objects together) from the sun and planets gradually changes Toutatis's orbit. That means a few hundred thousand years from now, the 4.6 kilometer (3 mile)-long by 2.4 km (1.5 mi)-wide rock may hit Earth. The impact wouldn't wipe out humans, but it could kill millions, says David Morrison, an astronomer at NASA. He adds, "I wouldn't want to be on Earth when it hits."
THREAT OF NEAR-EARTH ASTERIODS
AN ASTEROID ENTERS EARTH'S POTENTIALLY
THE SIZE OF ... ATMOSPHERE ... CAUSING ...
Dust and Continually Shooting stars
pebbles
A blue whale Every few Powerful shock-
centuries wave traveling
100 miles
A three-mile- Every 10 Global
wide rock million years devastation
SOURCE: NASA, ERIC ASPHAUG, WALL STREET JOURNAL, AND DAVID MORRISON
Answer About 439 new NEAs were detected between 2003 and 2004. (Answers will vary slightly.) |
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