2. Planets can't emit light by themselves, such as the eight planets in the solar system.

3. The light of the moon reflects sunlight, and stars can emit light by themselves, such as the sun, Vega and Sirius, so the moon is a satellite.

4. The moon, commonly known as the moon, is also called the moon. In ancient China, it was also called Taiyin, Xuantu, Chanjuan and Wangshu. It is the only natural satellite on the earth and the fifth largest satellite in the solar system.

The diameter of the moon is slightly more than a quarter of that of the earth, and its mass is about 1/8 1 of the earth.