Asteriods and the Earth

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Deputy Head

Subject: Asteriods and the Earth Mon Jun 05 2006, 12:53

Rolling rolling rolling keep those essays rolling - rolling rolling rolling - rolllll baaccck. Yeah I'm nuts but I'm trying to be amusing at the same time - is it working? You probably just think I'm even more nuts then where I started out at lol.

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Astronomers have found more than 200 asteroids with orbits that cross the earth's orbit. Some scientists project that several thousand of these earth-crossing asteroids may exist and that as many as 1500 could be large enough to cause a global catastrophe if they collided with the earth. Still, the chances of such a collision average out to only one collision about every 300,000 years.

Many scientists believe that collisions with asteroids or comets may have been responsible for at least one mass extinction of life on the earth over the planet's history. A giant crater on the Yucatan Peninsula in Mexico marks the spot where a comet or asteroid struck the earth at the end of the Cretaceous Period, about 65 million years ago. This is about the same time as the disappearance of the last of the dinosaurs. A collision with an asteroid large enough to cause the Yucatan crater would have sent so much dust and gas into the atmosphere that sunlight would have been dimmed for months or years. Reactions of gases from the impact with clouds in the atmosphere would have caused massive amounts of acid rain. The acid rain and the lack of sunlight would have killed off plant life and the animals in the food chain that were dependent on plants for survival.

The most recent major encounter between the earth and what may have been an asteroid was a 1908 explosion in the atmosphere above the Tunguska region of Siberia. The force of the blast flattened over 200,000 hectares (over 500,000 acres) of pine forest and killed thousands of reindeer. The number of human casualties, if any, is unknown. The first scientific expedition went to the region several decades later. This expedition and several detailed studies following it found no evidence of an impact crater. This led scientists to believe that the heat generated by friction with the atmosphere as the asteroid plunged toward the earth was great enough to make the object explode before it hit the ground.

If the Tunguska asteroid had exploded in a less remote area, the loss of human life and property could have been astounding. Military satellites-in orbit around the earth watching for explosions that could signal violations of weapons testing treaties-have detected dozens of smaller asteroid explosions in the atmosphere each year. In 1995 NASA, the Jet Propulsion Laboratory, and the U.S. Air Force began a project called Near-Earth Asteroid Tracking (NEAT). NEAT uses an observatory in Hawaii to search for asteroids with orbits that might pose a threat to the earth. By tracking these asteroids, scientists can calculate the asteroids' precise orbits and project these orbits into the future to determine whether the asteroids will come close to the earth.

Astronomers believe that tracking programs such as NEAT would probably give the world decades or centuries of warning time for any possible asteroid collision. Scientists have suggested several strategies for deflecting asteroids from a collision course with the earth. If the asteroid is very far away, a warhead could be used to blow it up without much danger of pieces of the asteroid causing significant damage to the earth. Another suggested strategy would be to attach a rocket engine to the asteroid and direct the asteroid off course without breaking it up. Both of these methods require that the asteroid be far from the earth. If an asteroid exploded close to the earth, chunks of it would probably cause damage. Any effort to push an asteroid off course would also require years to work. Asteroids are much too large for a rocket to push quickly. If astronomers were to discover an asteroid less than ten years away from collision with the earth, new strategies for deflecting the asteroid would probably be needed.

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Number 2 out of we'll see haha but all together making 20 - woo hoo! And it never ever stops lol.

Sources: Besides my knowledge and books I own - can be found here!: http://csep10.phys.utk.edu/astr161/lect/asteroids/collisions.html

Subject: Re: Asteriods and the Earth Tue Jun 06 2006, 10:30

Lol, such plans for so many essays and now the new rule - how must you be coping my dear? 50 points.

» Facts about Asteriods
» Are You Earth, Fire, or Air?
» Could an Asteroid Hit Earth?
» New Earth Discovered?
» If you were the last person on earth.....