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Halley's Comet (1P/Halley)
Halley's Comet (1P/Halley) The best-known periodic comet, returning to perihelion at average intervals of 76 years on a retrograde orbit (the time between returns ranges from 74 to 79 years). Comet Halley has been observed at every return since 240 bc. It is named after E.Halley, who in 1705 showed that comets seen in 1531, 1607, and 1682 were identical, and successfully predicted the return of 1758. In 1910 Halley's Comet passed 0.15 AU from Earth, reaching magnitude 0 and showing a 100° tail; the Earth passed through the tail on May20. At its most recent return, in 1986 (perihelion February9, closest to Earth 0.42 AU on April11), it reached 3rd magnitude and had a 10° tail. On this occasion, five space probes were sent to investigate it: Giotto, Sakigake, Suisei, and Vega 1 and 2. It was found to have an irregular nucleus measuring 16 × 8 km with an albedo of 0.04. Halley's Comet is the parent of the Eta Aquarid and Orionid meteor showers. Its perihelion is 0.587 AU, aphelion 35.3 AU, eccentricity 0.967, inclination 162°.2. The comet will next return to perihelion in 2061.
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"Halley's Comet (1P/Halley)." A Dictionary of Astronomy. 1997. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "Halley's Comet (1P/Halley)." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O80-HalleysComet1PHalley.html "Halley's Comet (1P/Halley)." A Dictionary of Astronomy. 1997. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-HalleysComet1PHalley.html |
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Halley's comet
Halley's comet or Comet Halley , periodic comet named for Edmond Halley, who observed it in 1682 and identified it as the one observed in 1531 and 1607. Halley did not live to see its return in 1758, close to the time he predicted. It reappeared in 1835 when it was carefully recorded by visual observers, and in 1910, when its long tail and outbursts of dust jets were observed photographically. For its most recent return in 1985 and 1986, astronomers observed it from the ground and from space. A massive observing effort (1982–89) including visual observations, photography, and studies of the area around the nucleus, was coordinated by the International Halley Watch. Japan, the European Space Agency, and the USSR sent spacecraft to study the comet; the Vega and Giotto probes revealed a darker-than-expected nucleus 8 km (5 mi) wide and 15 km (9 mi) long, and shaped like a potato.
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"Halley's comet." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "Halley's comet." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1E1-Halleysc.html "Halley's comet." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-Halleysc.html |
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Halley's comet
Halley's comet Bright periodic comet. It takes 76 years to complete an orbit that takes it from within Venus' orbit to outside Neptune's. It was observed by Edmond Halley in 1682; later he deduced that it was the same comet that had been seen in 1531 and 1607, and predicted its return in 1758. There are records of every return since 240 bc. In 1986, the Giotto space probe showed the nucleus to be an irregular object, measuring 15 × 8km (9 × 5mi), and consisting of ice.
http://lpl.arizona.edu/nineplanets/nineplanets/halley.html |
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"Halley's comet." World Encyclopedia. 2005. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "Halley's comet." World Encyclopedia. 2005. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O142-Halleyscomet.html "Halley's comet." World Encyclopedia. 2005. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-Halleyscomet.html |
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Halley's Comet
Halley's Comet a periodical comet with an orbital period of about 76 years, its reappearance in 1758–9 having been predicted by the English astronomer and mathematician Edmond Halley (1656–1742), who identified it. It was first recorded in 240 bc and last appeared, rather faintly, in 1985–6, when the European space probe Giotto took close-up photographs of the nucleus.
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ELIZABETH KNOWLES. "Halley's Comet." The Oxford Dictionary of Phrase and Fable. 2006. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. ELIZABETH KNOWLES. "Halley's Comet." The Oxford Dictionary of Phrase and Fable. 2006. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O214-HalleysComet.html ELIZABETH KNOWLES. "Halley's Comet." The Oxford Dictionary of Phrase and Fable. 2006. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O214-HalleysComet.html |
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