Astronomy Picture of the Day
Discover the cosmos! Each day we feature a different image or photograph
of our fascinating universe, along with a brief explanation written by a
September 24, 1995
Mimas: Small Moon with A Big Crater
Mimas is one of the smaller moons of
Saturn but shows one of the
largest impact craters!
In fact, if the impact had been much greater, it would have
disrupted the entire satellite. The large crater has been named Herschel
after the 1789 discoverer of Mimas,
William Herschel. Mimas' low mass produces a
surface gravity just strong enough to create a spherical body but
weak enough to allow such relatively large surface features.
is made of mostly water ice with a smattering of rock - so it is accurately
described as a big dirty snowball.
flew by in 1980 and took the above picture.
Tomorrow's picture: Orion's Horsehead Nebula
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