Asteroids are rocky and metallic objects that
orbit the Sun but are too small to be considered planets.
They are known as minor planets.
Asteroids are material left over from the formation of the
solar system. One theory suggests that they are the remains
of a planet that was destroyed in a massive collision long ago.
More likely, asteroids are material that never coalesced into
a planet. In fact, if the estimated total mass of all asteroids
was gathered into a single object, the object would be less
than 1,500 kilometers (932 miles) across - less than half the
diameter of our Moon.
Asteroids that are on a collision course with Earth are called
meteoroids. When a meteoroid strikes our atmosphere at high
velocity, friction causes this chunk of space matter to
incinerate in a streak of light known as a meteor. If the
meteoroid does not burn up completely, what's left strikes
Earth's surface and is called a meteorite.
Ceres, Davida, Eunomia, Europa, Gaspra, Hygiea, Ida, Interamnia, Pallas, Psyche, Sylvia, Vesta.