What is Halley s Comet What is Halley s Comet

Halley's Comet (periodic comet catalog number: 1P Halley) is a periodic comet that orbits the Sun once a year and is visible to the naked eye. It is named after the English physicist Edmund Halley (1656-1742) who first measured his orbital data and successfully predicted the time of return.

Halley's Comet has an orbital period of 76 79 years, and its next perihelion will be on July 28, 2061. Halley's Comet was the first recorded periodic comet, and at the latest in 240 BC or 466 BC, there were clear records of the comet's appearance in China, ancient Babylon, and medieval Europe, but it was not known at the time that it was a recurrence of the same comet. According to Zhu Wenxin's research:

From the seventh year of Qin Shi Huang (240 BC) to the second year of Xuantong of the Qing Dynasty (1910), a total of 29 records were recorded, and the calculation results were in line with the results.

Halley's Comet is the only short-period comet that can be seen directly from Earth with the naked eye, and the only comet that can be seen twice in a lifetime with the naked eye. Other comets that can be seen with the naked eye may be more spectacular and beautiful, but those are comets that only appear once in thousands of years. Halley's Comet last returned in 1986, and the next return will be in mid-2061.

At the time of its return in 1986, Halley's Comet became the first comet to be observed in detail by a spacecraft, providing first-hand information on the structure of the comet's nucleus and the mechanisms of comet emitting and tail formation. These observations support long-held assumptions about comet structure, in particular Fred Hewlett-Packard's "dirty snowball" model, which correctly speculates that Halley's Comet is a mixture of volatile ice such as water, carbon dioxide, and ammonia and dust. The information provided by this mission also significantly reforms and reconfigures the idea of these materials; For example, understand that the surface of Halley's Comet is mostly dusty, has no volatile substances, and is only a small part of ice.

The Orionid meteor shower is caused by the famous Halley's Comet.

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Problem description: How many years does it take to orbit the Earth?

Analysis: In ancient times, people thought that the appearance of comets was a bad omen, until the 17th century, when the British astronomer Halley began to calculate the orbits of comets, he found that the comets that appeared in 1682, 1607 and 1531 had similar orbits, and he judged that these three comets were actually the same comet, and predicted that it would appear again at the end of 1758 or early 1759. In 1759, the comet appeared.

Although Halley had died in 1742, the comet was called "Halley's Comet" in his honor.

Halley's comet has a return period of 76 years, with the most recent return in 1986.

The most famous comet in history is Halley's Comet. The current comet is crowned with the name of the person who first observed it, such as Comet Hale-Popper, and Halley's Comet is the star that was predicted.

Newton's Principia Mathematica of Natural Philosophy, published in 1686, hypothesized that some comets had closed orbits, i.e., would recur regularly; Halley wanted to test this hypothesis.

From 1695 onwards, he collected past observations, analyzed them using Newton's laws of motion, and found that the orbit of the comet observed in 1682 was very similar, and it should be the same comet. If this speculation is correct, then it should have reappeared in 1758, when Halley predicted the appearance of a comet for the first time in 1705, saying: If he did reappear in 1758, future generations will remember that the credit for the discovery of the comet was attributed to an Englishman.

He was right, on Christmas Day 1758 (which also happened to be Newton's birthday, what a beautiful coincidence), it reappeared in the eyes of the world, a little later than Halley**, and passed perihelion on March 14, 1759. Later, this most legendary comet, sure enough, took the name of this Englishman and is still used today.

The Halley's Comet is known to everyone as its famous 76-year cycle. However, if you think that as long as you know the year in which Halley's Comet returned, plus 76 years will be the year of its next return, you are not necessarily right. Due to the small mass of a comet, it is difficult to travel when it passes through larger planets such as:

Jupiter) is susceptible to the gravitational pull of the planet and changes its orbit; In addition, every time you pass near the Sun, you lose mass when exposed to the Sun, which also affects your orbit. Scientists speculate that Halley's comet has a cycle of about years to years. However, compared to other comets, Halley's Comet is still a very active and periodically stable comet.

Halley's Comet visited again in 1986, the first time that mankind entered the space age, and the Soviet Union, Japan, and the European Space Agency all sent spacecraft to greet it, and interestingly, NASA was absent from this event! Of these spacecraft, the European Space Agency's Giotto was the closest, and the nucleus was also photographed. The next Halley's Comet will visit again in 2061.