Word: comets
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Dates: during 1990-1999
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...spectral magnificence, the tail of a comet is about as close as you can get to nothing at all, a banner of dust so tenuous that a cubic mile's worth wouldn't fill a shoebox. Yet that near nothingness holds many secrets. Comets are leftovers from the creation of the solar system 4.5 billion years ago; they also delivered organic chemicals and water--the crucial building blocks of life--to the young Earth. Scientists would love, therefore, to get a bit of comet into the lab for analysis...
...Aaron touches the Nile with his staff, and it turns to blood. Egypt is then infested successively by frogs, gnats, flies, a pestilence on livestock, boils on people and beasts, hail, locusts and "a darkness that can be touched." Scientific skeptics have assigned them myriad natural explanations, including a comet and a volcanic eruption on the Mediterranean island of Santorini. The most ingenious effort is an ecological domino theory proposed in the 1950s by a scholar named Greta Hort: the Nile's many tributaries flood, infesting the great river with blood-red soil from the high plateaus and reddish micro...
...fact that the meteorite exists at all, says Kyte, also strongly suggests that it came from an asteroid, not from a comet, as many scientists still believe. He notes that comets strike the earth at such high speeds--many of them well over 100,000 m.p.h.--that they are usually completely melted and vaporized. But a typical asteroid hits at less than half that speed, and some fragments often survive. So why did this one turn up 5,400 miles away from the Yucatan impact site? Kyte believes it was flung by the explosion high above the atmosphere...
...Leonid meteor storm -- and while stargazers across the globe settle down for a romantic cascade of shooting stars, scientists and corporations scramble to save their satellites from the biggest Earth-bound bombardment the space age has ever seen. As you read this, tiny fragments from the Comet Tempel-Tuttle's tail are whizzing toward our unsuspecting planet at a dizzying 155,000 mph. You, of course, are protected by many miles of flammable, oxygen-rich atmosphere. The satellite your pager uses -- not to mention your phone company, your cable company and your government -- isn't so lucky. Our entire orbital...
...Leonid showers are alike, however. As Donald Yeomans, an astronomer at the Jet Propulsion Laboratory, notes, "Most of the particles are following closely behind the parent comet. That's where the gathering is thickest, and it's only when the comet is in Earth's neighborhood that we get intense showers or storms...