竹墨韵风 | 编译
Asteroids are objects composed of rocky or metallic materials and are mainly found orbiting the Sun in a region called the asteroid belt between Mars and Jupiter. Some are large － the biggest is Ceres with a diameter of nearly 600 miles (966km) － and are sometimes called minor planets or planetoids. There are millions of small asteroids. The smallest are sometimes called meteoroids. It's thought that asteroids are material leftover from the time that the planets formed.
Objects falling through the Earth's atmosphere are called meteors. If they survive and hit the Earth's surface they are called meteorites.