asteroid

Everyday

1. An asteroid is a rocky or metal object in space, smaller than a planet, that goes around the Sun. tree →
2. Asteroids range from the size of a pebble or boulder to hundreds of kilometres across. tree →

In the lessons

In science (space) most asteroids are in the asteroid belt between Mars and Jupiter. Scientists think a huge asteroid that hit the Earth helped to wipe out the dinosaurs. A small piece that falls through the air and glows is a meteor; one that lands is a meteorite. Space agencies watch for asteroids that come near Earth.

Examples

• Most asteroids orbit the Sun between Mars and Jupiter. tree →
• A giant asteroid may have caused the dinosaurs to die out. tree →
• Some asteroids are as big as a city. tree →
• Scientists track asteroids that come close to Earth. tree →
• A spacecraft landed on an asteroid and collected dust. tree →
• Asteroids are smaller than planets and moons. tree →

Note

Countable. Asteroid, comet, meteor: an asteroid is rocky; a comet is icy and grows a tail near the Sun; a meteor is the streak of light («shooting star») when a small piece burns up in the air. A meteorite is a piece that reaches the ground.