Astronomy: Halley's Comet

Astronomy: Halley's Comet
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Solar System
Halley's Comet Halley's Comet is the only known short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years, though with the majority of recorded apparitions (25 of 30) occurring after 75–77 years. It last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061.

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Commentary

Source: Wikipedia (CC BY-SA)
Halley's Comet Halley's Comet is the only known short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years, though with the majority of recorded apparitions (25 of 30) occurring after 75–77 years. It last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061. Officially designated 1P/Halley, it is also commonly called Comet Halley, or sometimes simply Halley.

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Why Halley's Comet matters: Understanding our cosmic neighbourhood helps us learn about planetary formation, the conditions for life, and ultimately our place in the universe. Halley's periodic returns to the inner Solar System have been observed and recorded by astronomers around the world since at least 240 BC, b ut it was not until 1705 that the English astronomer Edmond Halley understood that these appearances were re-appearances of the same comet. As a result of this discovery, the comet is named after Halley. In March 1986, during its latest visit to the inner Solar System, Halley's Comet became the first comet to be observed in detail by a spacecraft, ESA's Giotto mission, providing the first observational data on the structure of a comet nucleus and the mechanism of coma and tail formation. These observations supported several longstanding hypotheses about comet construction, particularly Fred Whipple's "dirty snowball" model, which correctly predicted that Halley would be composed of a mixture of volatile ices—such as water, carbon dioxide, ammonia—and dust. The missions also provided data that substantially reformed and reconfigured these ideas; for instance, it is now understood that the surface of Halley is largely composed of dusty, non-volatile materials, and that only a small portion of it is icy. It was also visited by the two spacecrafts of the Vega program, Vega 1 & 2, on 6 and 9 March, respectively. They went as close as 8,890 km (5,520 mi), and 8,030 km (4,990 mi), providing data on Halley's dimensions, shape, temperature, and surface properties.

Commentary

Source: Internal
Deep dive: Halley's Comet As a result of this discovery, the comet is named after Halley. In March 1986, during its latest visit to the inner Solar System, Halley's Comet became the first comet to be observed in detail by a spacecraft, ESA's Giott o mission, providing the first observational data on the structure of a comet nucleus and the mechanism of coma and tail formation. These observations supported several longstanding hypotheses about comet construction, particularly Fred Whipple's "dirty snowball" model, which correctly predicted that Halley would be composed of a mixture of volatile ices—such as water, carbon dioxide, ammonia—and dust. The missions also provided data that substantially reformed and reconfigured these ideas; for instance, it is now understood that the surface of Halley is largely composed of dusty, non-volatile materials, and that only a small portion of it is icy. It was also visited by the two spacecrafts of the Vega program, Vega 1 & 2, on 6 and 9 March, respectively. They went as close as 8,890 km (5,520 mi), and 8,030 km (4,990 mi), providing data on Halley's dimensions, shape, temperature, and surface properties. Source: https://en.wikipedia.org/wiki/Halley%27s_Comet (Wikipedia, CC BY-SA)