What does a comet mean?

Comet, commonly known as "broom star" in Chinese, is one of the small celestial bodies in the solar system. It consists of frozen substances and dust. It is visible when it is close to the sun. The heat of the sun makes the comet material evaporate, forming a hazy coma around the ice core and a tail composed of thin material flow. Due to the pressure of the solar wind, the tail always points away from the sun. Before 1995, comets were arranged in English capital letters according to the annual discovery order. For example, the first comet discovered in 1994 was 1994a, and so on. After a period of observation, the orbit of the comet was determined and corrected, and the perihelion of the comet was ranked after the year with Roman numerals I and II (this number is usually compiled two years after the end of the year). Like a shoemaker? 6? The serial numbers of comet Levi-9 are 1993e and 1994 x.

In addition to numbering, comets are usually named after the discoverer's surname. A comet can only be named after three discoverers at most. The English name of comet Shoemaker-Levy 9 is Shoemaker-Levy 9.

Starting from 1995, the International Astronomical Union (IAU) refers to the naming rules of asteroids and adopts a new numbering method of comets arranged alphabetically once every two months. If I and Z are removed from all English letters, the order of the remaining 24 letters is unnecessary, such as A 65438+ in the first half of June, B 65438+ in the second half of 10, and so on to y 65438+ in the second half of February.

Later, the comets discovered in the same month and a half were numbered 1, 2, 3 ... In addition, in order to facilitate the identification of the status of comets, a mark was added before the numbers:

Could be an asteroid.

For short-period comets with more than P/ confirmation 1 time, add the general table number of periodic comets before p (for example, Halley's comet is 1P1982u1or1p for short).

C/ Long-period comets (with a period of more than 200 years, such as Comet Haile Popper C/ 1995 O 1)

A comet whose X/ orbital elements have not been calculated.

D/ Comets that never return or may have disappeared (such as shoemakers? 6? Comet levy 9 is D/ 1993 F2)

Satellites with S/ newly discovered planets

If a comet breaks and splits into more than one nucleus, add -A, -B ... after the number to distinguish each nucleus. For the returning comet, if it is observed that the comet returns again, a serial number given by the IAU asteroid center should be added before P/ (or possibly D/) to avoid re-marking the comet when it returns. For example, Halley's comet has the following signs:1p/1682q1=1p/10a2 =1p/1982u1