Asteroids are small objects in our solar system that orbit the sun. They are so small that they are much smaller than Earth and its moon. In fact, if Earth and its moon were combined, they would be smaller than a nickel, while Ceres is smaller than a sesame seed. There are 150 known asteroids, many of which have moons. The first asteroid-moon system was discovered in 1993 when the asteroid Ida and its moon were discovered.
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