A night of shooting stars. (Astronomy).Thousands of people in North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. who got up early on Nov. 18 were dazzled by a memorable sky show. White, yellow, blue, and green fireballs A number of sightings described as "green fireballs" were reported in the skies of the southwestern United States, particularly New Mexico, beginning in late 1948. Such sightings worried some in the government, who noted that the reports were often made near to sensitive research , some leaving behind smoke trails, streaked across the sky. For sky watchers in the United States, it was probably the best Leonid meteor shower since the 1966 storm and is unlikely to be matched for another 3 decades. As several teams of researchers had predicted, residents of eastern Asia and Australia were treated to a veritable storm, with several thousand meteors an hour illuminating the sky (SN: 11/10/01, p. 293). The Leonid shower happens every November, when Earth plows through bands of dusty debris, or meteoroids, shed over the centuries by Comet 55P/Tempel-Tuttle. The meteoroids burn up in Earth's atmosphere, creating the spectacle. According to a Nov. 19 circular of the International Astronomical Union “IAU” redirects here. For other uses, see IAU (disambiguation). The International Astronomical Union (IAU) unites national astronomical societies from around the world. , the shower had two peaks. The first occurred about 5:30 a.m. EST EST electroshock therapy. EST abbr. electroshock therapy , when Earth intercepted a meteoroid meteoroid: see meteor. stream that astronomers believe the comet ejected in 1767. This peak produced about 800 meteors an hour. However, North Americans near the bright lights of major cities probably saw no more than 100 an hour, says Brian G. Marsden Brian G. Marsden (born August 5,1937) is a British astronomer, the longtime director of the Minor Planet Center(MPC). He specializes in celestial mechanics and astrometry, collecting data on the positions of asteroids and comets and computing their orbits, often from minimal of the Harvard-Smithsonian Center for Astrophysics The Harvard-Smithsonian Center for Astrophysics (CfA) is located in Cambridge, Massachusetts. It consists of the Harvard College Observatory and the Smithsonian Astrophysical Observatory. The Center is located at 60 Garden Street. in Cambridge, Mass. The other, much higher peak of several thousand meteors per hour occurred around 4:30 a.m. Japan Standard Time on Nov. 19, when Earth plowed through a debris stream left behind in 1866. Both peaks occurred about half an hour later than some researchers had calculated, but "I think the predictions fared very well indeed," says Marsden. "This year was the first real test of the [debris]-trail model," he says. That model assumes that the dust expelled by Tempel-Tuttle each time it nears the sun forms a separate stream of debris that remains relatively narrow for centuries. During the Leonid shower, several observers reported flashes of light from the moon. Because the moon has no atmosphere, meteoroids strike the lunar surface instead of disintegrating. Most of the dusty debris is composed of tiny particles, but the ones that generated the lunar explosions visible from Earth could have been as heavy as 10 kilograms, researchers estimate. --R.C. |
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