An asteroid is a large, irregularly shaped object in space that orbits our Sun. If one of these giant rocks ends up on a collision course with Earth, we are in for big trouble.

An asteroid is like a comet. However, while comets are mostly made of ice, asteroids are made up of rock or even metal. This makes them dangerous because they can cause a lot of damage if they collide with a planet. The craters on the Moon were formed by asteroids and some think it was an asteroid that wiped out the dinosaurs. Around a million asteroids are located between Mars and Jupiter in an area called the “asteroid belt.”

Definitions of asteroid
  1. noun
    any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)
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    Apollo asteroid
    an asteroid whose orbit crosses the Earth's orbit
    the largest asteroid and the first discovered
    a large asteroid; the second asteroid to be discovered
    the brightest asteroid but the fourth to be discovered
    an asteroid discovered in 1977; it is unique in having an orbit lying mainly between the orbits of Saturn and Uranus
    type of:
    minor planet, planetoid
    any of numerous small celestial bodies that move around the sun
  2. adjective
    shaped like a star
    synonyms: star-shaped
    angular, angulate
    having angles or an angular shape
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