Sun grazers: a thousand comets and counting.While staring virtually nonstop HP's brand name for its fault-tolerant servers, which range in size from four CPUs to 4,000 CPUs. The NonStop line was created by Tandem Computers, which was acquired by Compaq, which later became part of HP. at the sun for nearly a decade, the Solar and Heliospheric Observatory The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched on an Atlas IIAS launch vehicle on 2 December 1995 to study the Sun, and began normal operations in May 1996. (SOHO Soho (sōhō`, sə–), district of Westminster, London, England, known for its continental restaurants. Once a fashionable quarter, it became popular among writers and artists in the 19th cent. ) satellite has discovered hundreds of comets--roughly half of all that are known. In August, an amateur astronomer analyzing SOHO images found the 999th and 1,000th of these icy chunks detected by the spacecraft. Toni Scarmato, a high school teacher and a graduate student at Bologna Bologna (bōlô`nyä), city (1991 pop. 404,378), capital of Emilia-Romagna and of Bologna prov., N central Italy, at the foot of the Apennines and on the Aemilian Way. University in Italy, identified the two comets Non-periodic comets are seen only once. They are usually on near-parabolic orbits that will not return to the vicinity of the Sun for thousands of years, if ever. Periodic comets usually have elongated elliptical orbits, and usually return to the vicinity of the Sun after a number as part of the Kreutz group of sun-grazing comets. About 85 percent of the comets found by SOHO belong to this group, whose members have similar orbits and pass within 800,000 kilometers of the sun's surface, less than one-seventieth Mercury's distance from the sun. At this distance, the sun's heat and gravity easily break comets apart, and each member of the Kreutz family may be a fragment of what had once been a single large comet. Indeed, many comets in this family are so small--about the size of a house--that they can't be seen with ground-based telescopes. An instrument aboard SOHO can detect these comets because it has a large field of view and masks the sun's blinding light.--R.C. |
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