Can asteroids have moons?

Planets can have moons but can large asteroids have them too?

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A Galileo spacecraft image of asteroid 243 Ida. The tiny dot to the right is its moon, Dactyl.

A Galileo spacecraft image of asteroid 243 Ida. The tiny dot to the right is its moon, Dactyl.

Asked by Nikita Kinzer

Yes, asteroids can have moons. In 1993 the Galileo spacecraft was the first to identify a moon orbiting an asteroid. The moon, called Dactyl, is just over a kilometre across and is the natural satellite of asteroid 243 Ida, which can be found in the asteroid belt.

Since then, many more asteroid-moon systems have been discovered, with us locking down over 200 so far. The location of an asteroid-moon system is not limited to the main asteroid belt; asteroids closer to Earth and beyond the orbit of Jupiter are also known to have natural satellites. Asteroids are also not limited to just one moon and some have been found to have more than one body orbiting them.

Answered by Zoe Baily at the National Space Centre

Image credit: NASA

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