Io has big volcanoes for a small moon

Just about everybody who knows about astronomy, specifically in the category of Solar System planets, knows that there are big volcanoes on Jupiter's moon Io.  The volcanoes were discovered because of a big plume of sulfurous spew that was spied in a Voyager image.  So when the New Horizons satellite stopped by Jupiter on its way to Pluto, it took a look at Io, and saw more volcanic plumes arching high into the Jovian sky.

A five-frame "movie", repeated over and over, shows the volcanic plume over Io.  There are certainly strange places in the Solar System, and Io is one of the strangest.