Salt Lake City
UFO conspiracy theorists probably won鈥檛 be surprised to learn of evidence
that an extraterrestrial object crashed at the US Air Force鈥檚 top-secret 鈥淎rea
51鈥� in Nevada. But they may be disappointed to discover that the alien invader
was a comet some 6 kilometres across, and that it hit the ground 367 million
years ago.
Area 51 looms large in UFO mythology as the alleged nerve centre of the US
military鈥檚 research on aliens. Residents of Rachel, a small town nearby, have
even named a local road the 鈥淓xtraterrestrial Highway鈥�.
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Charles Sandberg of the US Geological Survey in Menlo Park, California, last
week told the Geological Society of America鈥檚 meeting in Salt Lake City that
Rachel, the highway and Area 51 all lie in a comet impact zone. He has found
grains of shocked quartz that are produced only in major impacts, and a layer
rich in the metal iridium, also a signature of an impact.
Sandberg has been unable to explore much of the area because of security
restrictions. But if his estimate for the crater鈥檚 diameter鈥�100
kilometres鈥攊s correct, it is among the largest known.