Asteroids are lumps of rocks in space. Most of these rocks are located in a belt between Mars and Jupiter. The largest asteroid is Ceres, which is considered a dwarf planet. It is about 600 miles across. There are tens of thousands of these bodies in the asteroid belt. They are smaller than planets but larger than meteoroids. Vesta is another large asteroid in the asteroid belt. Since it is not round, it is not considered a dwarf planet.
Meteors are sometimes called shooting stars and falling stars, even though they are not stars. They are bodies from space that enter the orbit of a planet or moon. Many meteors come from 'meteor trails' created by comets as they orbit. Bits of comets break off to form this trail. Sometimes they appear in the night sky as a streak of light. Friction makes the meteoroids heat up and give off a hot, reddish glow. They usually burns up before reaching a planet or moon. Large meteorites don't burn up completely. The largest meteorites leave craters or deep pits on the our Moon and the Earth. Check out the this year's meteor showers at Almanac.com
Comets are mostly dust and ice. They are like a dirty snowball. The gas and dust shine more intensely as it gets closer to the sun. A comet's tail can be more than a million miles long. The core of a comet is called the nucleus. The tail of the comet comes from the nucleus. The tail is made up of gas and particles that escape the nucleus as it heats up.