Word: asteroids
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Meteors, which are asteroids or cometary debris that has entered the atmosphere, continually shower the earth. Most of them are small and either break up or are burned to ash by frictional heat generated by their plunge through the atmosphere. But, explains Shoemaker, the incineration of larger asteroids is far more violent. An asteroid 80 ft. across, striking the atmosphere at 50,000 m.p.h., compresses the air in its path so much that in effect the asteroid is stopped dead in its tracks, converting kinetic energy almost instantaneously into heat, light and a powerful shock wave. That causes a tremendous...
...calculations suggest that asteroids packing the explosive energy of one megaton should enter the atmosphere on an average of once every 30 years, larger asteroids with a 20-megaton punch every 400 years, and a 1 km, 10,000- megaton comet or asteroid once in 100,000 years...
This century has already seen a major meteorite blast. In 1908, either an asteroid or a comet exploded about five miles above the remote Stony Tunguska River region of Siberia, igniting and flattening trees over hundreds of square miles. From descriptions of the blast and photographs of the damage, scientists have estimated that the object was at least 200 ft. across and caused a twelve-megaton explosion...
What if a large asteroid or comet is discovered heading toward the earth? At the AGU meeting, Shoemaker and Colleague Alan Harris, of the Jet Propulsion Laboratory in Pasadena, Calif., suggested that the intruder could be diverted by landing a thrusting device on it. As a last-ditch effort, they say, a small nuclear warhead could be detonated on or near it. Says Shoemaker: "We have the technology to do that right now." But if the explosion simply broke the meteorite into large chunks, the danger would only be multiplied. "The more prudent solution," says Harris, "is to burrow...
During the past few years, evidence has been accumulating to support Physicist Luis Alvarez's theory that a giant comet (or asteroid) struck the earth 65 million years ago, pulverizing a huge area and spewing so much debris into the atmosphere that the skies darkened for months, temperatures dipped, and much of the life on earth--most notably the dinosaurs--perished. It was the demise of the dinosaurs, many evolutionists believe, that enabled man's tiny mammalian ancestors to emerge from hiding, occupy the environmental niches left vacant by the great beasts and other destroyed species, and evolve into Homo...