About the constellation meteor shower?

In astronomy, a large group of meteoroids orbiting the sun along the same orbit is called a meteor group. When the meteor group meets the earth, people will see that the number of meteors in a certain area of the sky increases significantly within a certain time range, which greatly exceeds the number of meteors that usually appear occasionally, just like rain. This phenomenon is called meteor shower. When a meteor shower occurs, it can be as high as ten to dozens per hour, and when a meteor shower occurs, it can be as high as thousands or even tens of thousands per hour.

Meteor showers are mainly caused by comets. When a comet orbits the sun and passes near the perihelion of its orbit (the closest point to the sun), due to the thermal radiation of the sun, a large number of debris emitted by the comet will form a debris-intensive area in its orbit with the operation of the comet. When the earth passes through this region, a large number of debris will enter the atmosphere at high speed and have fierce friction, and the temperature will rise sharply, making the debris burn and emit bright light. When the radiation point of a meteor (the intersection of all the opposite extension lines of the meteor trajectory) is in the sky area of a certain constellation, it is called a meteor shower of a certain constellation, such as Leonid meteor shower, Perseid meteor shower, Orion meteor shower, etc.

There are many records about meteor showers in China ancient books. The record of "fifteen years in Guangxi, starry night like rain" in the chronicle of bamboo books refers to a meteor shower in Shang Dynasty in the 6th century BC/KLOC-0, which is also the earliest meteor shower record in the world. The Spring and Autumn Annals recorded a meteor shower in the seventh year of Duke Zhuang of Lu (687 BC): "In summer and April, in Xinmao, at night, the stars disappear, and the stars are like rain." This is the earliest record of Lyra meteor shower. The Book of Song recorded a meteor shower at the end of February (April 9, 433 AD) in Yuanjia, Liu Song in the Northern and Southern Dynasties: "A meteor as big as a peach left Tianjin Gate and entered the Purple Palace. In a short time, there were thin meteors or five or three meteors in a row, and another big meteor flew out of the purple palace, which made people feel like Beidou Kui. After a while, another big meteor came out, crossed the cable, crossed the sky and the city wall, and the meteor went north until dawn. " This is an observation record about the η meteor shower in Aquarius.

The appearance time and orientation of many celestial phenomena can be predicted in advance according to calculation, but the prediction level of the size and accurate time of meteor shower by modern science is not satisfactory. Leonid meteor shower has appeared on the earth 1799, 1833 and 1866. According to the law of the return of Comet Temple-Tuttle after about 33 years (orbiting the sun 1 week), it is predicted that the meteor rainstorm will come to the earth again in 1899, and will exceed 65,438. The result is disappointing: there is only sporadic light rain, only 40 times per hour. For the Leonid meteor shower of 1998, the maximum center time is predicted to be 0 1 18+0 1 Beijing time, when the radiation point is very low in the west and slightly higher in the east of China. It coincides with the end of the lunar calendar and there is no moonlight interference. In the second half of the night, you can observe the second half of the meteor shower, which is a rare observation opportunity. However, when people look up at the sky as scheduled, they can only see meteors without rain. The meteor shower occurs around 17+0 1. It is believed that the dense area of comet debris may deviate due to the gravitational force of the planet, which changes the trajectory of meteor group. In order to predict meteor showers more accurately, astronomers need to make greater efforts in exploring the mechanical and physical mechanisms of meteor swarms.

Meteor shower is a godsend beauty that can be feasted on. Meteor shower will not directly harm people on the ground, because the solid particles in the debris-intensive area formed in Xiangxing orbit are very small, and when they break into the earth at a high speed of tens of kilometers per second, they will be rubbed and burned in the atmosphere of tens of kilometers on the ground. However, meteor storms pose a threat to the safety of spacecraft in the earth's atmosphere. Before each meteor shower comes, it is a big headache for the people concerned.