Jupiter’s sixth moon Europa was discovered in 1610 by Galileo Galilei, and is named after a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the queen of Crete.
The Galilean moon Europa orbits Jupiter between Io and Ganymede.
Europa is about the same size as Earth’s moon.
It has a surface of ice, though ice probably makes up only 10 percent of its composition.
The other 90 percent is silicate rock.
A system of low ridges covers Europa, making it look like a cracked egg. Its relatively smooth surface is believed to be caused by an ocean of liquid water beneath the thin crust of ice.
The ocean remains liquid because Europa’s neighbor Ganymede acts like our Moon, causing ocean tides.
The motion of the water is sufficient to keep it liquid under the thin ice.