Comet Halley
| Comet Halley | |
 Halley's Comet, photographed March 8, 1986 by W. Liller to Easter Island. | |
| Orbital characteristics A | |
|---|---|
| Time | JJ 2449400.5 February 17, 1994 |
| Semi-major axis | 17.9 AU |
| Eccentricity | 0,96727 |
| Perihelion | 0.58721 AU |
| Aphelion | 35.33 AU |
| Period | 76.09 a |
| Tilt | 162.238 |
| Last perihelion | February 9, 1986 6 h 40 min UT |
| Next perihelion | July 28, 2061 |
| Discovery | |
| Discoverers | Known since prehistoric times. Named in honor of Edmond Halley. |
| Date | 1758 (first predicted perihelion) |
| Designations | 1P/Halley |
Comet Halley (1P/Halley) is the most famous of all comets. Its semi-major axis is 17.9 AU (about 2.7 billion kilometers), its eccentricity is 0.97 and its period is 76 years. Its distance from the perihelion of 0.59 AU is the distance and the aphelion is 35.3 AU.
Summary |
History
Identification
In 1705 , Edmund Halley published a book arguing that the comets that had appeared in the sky in 1531 , 1607 and 1682 were in fact one and the same comet. Explaining that the trip on a comet elliptical orbit , it takes 76 years to complete one revolution around the Sun. Halley predicted it would in 1758.
In 1757, Lalande , assisted by Nicole-Reine Lepaute , and based on formulas developed by Clairaut , decided to calculate the deviations of the comet due to the large planets. He foresaw a delay of 518 days due to Jupiter and Saturn had 100 days. So he announced the return of the comet, not in 1758 but in 1759 with a transition to perihelion in April 1759, with an uncertainty of a month. When the comet reappeared in December 1758 with a perihelion passage on 13 March 1759 , it was a triumph. This prediction allowed to sit permanently in France Newtonian mechanics, the theory of vortices of Descartes finally falling into oblivion. On the proposal of Nicolas Louis de Lacaille , it is called "Halley's comet Passages famous historical We can go back in time and assume the time Halley's comet should theoretically appear in the sky. According to the appearances of comets recorded by the elders, a comet was observed by men in 240 BC. BC It is possible that this is the comet Halley. According to Jacques Gernet , it was also discovered in China in the Kingdom of Yue in 467 BC. BC , which would be the first appearance is listed. It was described in 837 as it passes the most spectacular during historical times (about 3 million kilometers), both in Chinese, Japanese and European, including The Astronomer , author of a chronicle of the life of Louis the Pious. It could also be observed in the year 1066. A comet indeed attracted the attention of the army of William the Conqueror and is found on the famous Bayeux Tapestry , which depicts the Norman conquest of England. We know much more about the comet Halley from the Giotto spacecraft has probed the heart. Launched in 1985 , the probe's mission was to photograph the comet nucleus. Giotto came within 600 km of the nucleus peanut-shaped with dimensions of 16 8 7 km, it was a first in the history of astronomy. Giotto was able to see two large geysers of gas that fed the coma and tail. On his last visit, it was determined that its core is very dark, with an albedo of about 3%. Photos from the Giotto spacecraft are valuable data for understanding the formation of comets and the mechanism of sublimation approach the Sun. The last three visits of Halley's Comet back in 1835 , 1910 and 1986 , its next perihelion passage is expected on 28 July 2061 . 
Description
Observation Dates
- Abb de la Caille, On the calculation of the elements of the theory of the comet that now appears , Memoirs of mathematics and physics from the records of the Royal Academy of Sciences of the year MDCCLIX, P. 522 ff (May 12, 1759).
- Jacques Gernet, Le Monde Chinese, 3rd Volume, p. 146
- Comet 1 / P Halley , Webastro, July 15, 2010. Accessed March 17, 2011
- tablet in the British Museum
External Links
- (In) The Giotto mission
- (In) Halley's Comet
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