An asteroid is not the same as a comet. While they both fly through space, an asteroid is made of metal and rock, while a comet is made of rock, dust and ice. Asteroids exist closer to our sun, which warms them as they orbit around it. Comets form away from the sun. When they fly closer to the star, its warmth melts its ice to create its familiar tail. Meanwhile, a meteorite is a small particle from an asteroid or comet that survives entry through the Earth’s atmosphere. Experts believe that asteroids and comets formed at the beginning of our solar system, some 4.5 billion years ago.
Pictured here is Vesta in 3-D as imagined by the Dawn spacecraft. Vesta is believed to be one of the main sources of meteorites that fall to our planet. It is currently some 117 million miles from Earth.