英语行星作文 60词行星的英语作文 今天就要 今晚要!

A planet, as defined by the International Astronomical Union (IAU), is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighboring region of planetesimals. There are eight planets in the Solar System. In increasing distance from the Sun, they are: Mercury ,Venus, Earth, Mars, Jupiter, Saturn ,Uranus ,Neptune.