A comet is a small body of icy and dusty matter, which revolves around the Sun. When a comet comes near the Sun, some of its material vaporizes, forming a large coma of tenuous (thin and wispy) gas, and often a tail. As it evaporates, the orbital path of the comet becomes filled with debris from the comet's nucleus. Annual "meteor showers" (up to several meteors per minute) occur every year at about the same time when the Earth's orbit crosses the orbits of comets. Most annual meteor showers are named for the constellation from which the meteors appear to radiate. For example, the Leonids meteor shower in mid-November appears to radiate from the constellation Leo, the Lion (upper left).

The term asteroid is a synonym for "minor planet." The asteroid belt is located between the orbits of Mars and Jupiter.