Comet.

A comet is a celestial body with very strange morphological changes. When it appears in a clear night sky, it has a pointed head and a long and bright "tail" shaped like a broom. The Chinese meaning of "Hui" is broom. Therefore, Chinese people also call it the "broom star". Currently, the total number of comets that have been discovered is about 1,600, and some estimate that there are about 100 billion comets in the entire solar system.

Introduction to comets

Comets refer to celestial bodies moving around the sun that enter the solar system and whose brightness and shape change with the change of the solar distance. They have a unique cloud-like appearance. Comet is divided into three parts: nucleus, coma and tail. The comet's core is composed of icy material. When the comet approaches the star, the comet's material sublimates, forming a hazy coma and a tail composed of a thin flow of material around the icy core. Due to the pressure of the solar wind, the comet's tail always points away from the sun, forming a very long tail.

The tail of a comet is generally tens of millions of kilometers long, and the longest can reach hundreds of millions of kilometers. The comet is shaped like a broom, so it is commonly known as a broom star. The orbits of comets are mostly parabolic or hyperbolic, and a few are elliptical. At present, more than 1,700 comets have been discovered orbiting the sun. The famous Comet Halley takes 76 years to orbit the sun.

On February 21, 2014, a research team from Kyoto Sangyo University in Japan discovered the presence of ammonia on the comet. According to the latest reports, scientists recently discovered some chemical residues belonging to the comet "67P/Churyumov-Gerasimenko" on the Rosetta spacecraft tracking the comet.