Comet is a kind of low-mass celestial body that is easy to observe in the universe. It is mainly composed of dust and ice in the universe, and its length ranges from tens of kilometers to thousands of kilometers. When it passes near a star, it will pull out a long tail made of ice and reflect it in the light of the star, which looks very spectacular.
Man-made satellite is an unmanned spaceship, which runs around the earth in space. Satellites can be divided into communication satellites, meteorological satellites, reconnaissance satellites, navigation satellites, geodesic satellites and interception satellites. These artificial satellites with different uses have made great contributions to mankind.