Ida and Dactyl

Even an asteroid can have a moon. This asteroid is called Ida and has an average diameter of 31 km. It is orbited by the small moon Dactyl being just 1.4 km in diameter. Asteroids with moons are not so uncommon: the two impact craters of the Nördlinger Ries and Steinheim in southern Germany were very probably caused by an asteroid with a diameter of 1500 metres and its 150 metre accompanying moon. Ida is a typical asteroid belt object. This image was composed by Sun.org from photos taken during NASA's Galileo mission fly-by.

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