Mike, age 11 Dear Mike, A comet is a small icy body that orbits the sun in large highly elliptical orbits. Comets spend most of their time in the cold outer solar system, but occasionally travel into the warm inner solar system. They consist of very small rocky cores, surrounded by a coma of ice, gas, and dust. When a comet approaches the sun, its heat causes the gas and ice to vaporize and form a bright tail. An asteroid is usually a small rocky body, about 10 to 1000 km in diameter.
Most asteroids orbit the sun between Mars and Jupiter in an area called the asteroid belt.
Most asteroids are made of silicate rocks and minerals with a little metal, but some are mostly metal. A meteorite is an ancient primitive rock, most of which come from asteroids. Meteorites represent the building blocks of planets and, in some cases, life. I think comets are very cool. Sue, age 12 Dear Sue, Comets are the oldest, most primitive bodies in the Solar System.