The Solar System


What is an asteroid?

Asteroids are relatively small, primarily rocky or metallic chunks of matter that orbit the Sun. They are like planets, but much smaller; the largest asteroid, Ceres, is only about 580 miles (930 kilometers) across, and only ten asteroids larger than 155 miles (250 kilometers) across are known to exist in the solar system. While most asteroids are primarily composed of carbon-rich rock, some are made at least partially of iron and nickel. Aside from the largest ones, asteroids tend to be irregular in shape, rotating and tumbling as they move through the solar system.


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