It belongs to a kind of periodic comet, which is named after its short revolution period.
The operation period around the sun is less than 200 years, and the orbit is elliptical or hyperbolic. Some people think the latter is Jupiter Long-period comet It is also believed that it was originally an elliptical orbit, but became a hyperbola due to planetary perturbation, so this comet has enough speed to change its orbit shape, or even escape from the solar system. By 1979, short period comets accounted for more than 20% of the 658 comets recorded. Comets with elliptical orbits have obvious periodicity. The famous Halley's Comet has a revolution period of 76.1 years, and the last perihelion time was March 1910; The shortest cycle is Comet Enke (comet Encke), with a cycle of 3.3 years. The last perihelion was in June 1977 (there was also a return in 2013). Most short period comets have a period of about 7 years Short period comets are believed to originate from Ancient cypress belt , that is 35 away from the sun Astronomical unit In the range of 1000 astronomical units, some long-period comets become short period comets due to gravitational perturbation. Their orbits are usually stable in this wide range, but the gravity of the outer planets will occasionally interfere with them, making their orbits become elliptical orbits with high eccentricity close to the sun, but this situation is difficult to predict. And because of their low reflectivity, Optical telescope It is also difficult to observe in advance. But when comet After entering the inner side of the solar system and being heated, the ejected gas and dust form a comet surrounding the core, making their volume expand and easy to detect. All comets are thought to have similar composition and are basically formed from the same source. They were once described as Dirty snowball (dirty snowballs), but after the detailed study of Halley's Comet in 1986, due to its complex structure, it was called Ice mud ball (Icy mud ball) can be described more accurately. The core is mainly composed of volatile ice, a large amount of water mixed with dust and hydrogen carbide. The only comet nucleus that has been carefully studied（ Halley's Comet ）Because the surface is covered with black hydrogen carbide, it is darker than coal. until Giotto Before Haley's core was photographed in the 1986 mission, it was considered to have high albedo because of its ice content. Because of the low albedo, the size and mass of the cometary nucleus were re evaluated, and the estimated value was revised upward. Because approaching the sun increases the temperature, leading to the sublimation of volatile ice in the core, the released gas and dust form a cloud surrounding the core, called a comet. The gas and dust still connected with the comet become the comet tail. The heavier dust forms a curved or fan-shaped dust tail. Other gas components become ion tails due to the action of the solar wind. The orbital period of short period comets is usually several years to decades (the upper limit is 200 years). They mainly have two families: the Jupiter family with a period of less than 20 years and the Harley family with a period of 20 to 200 years. Most short period comets tilt the ecliptic at an angle of less than 350 degrees, and once discovered, they can usually correctly predict their orbits. However, there are still some uncertain factors to be added to the orbit calculation. One of the main factors is the gravity disturbance caused by the giant planets in the solar system. In extreme cases, it will also cause the core fragmentation, or SL-9 Crashed into Jupiter and was destroyed. The other mechanism is still unclear, and is rarely used for prediction. The thrust generated by the eruption of core gases and the volatilization of compounds may provide comet power like nozzles. Although it is weak, it will also affect the orbit of comets as long as the time is long enough. 
