Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core. It has a tenuous atmosphere composed primarily ofoxygen. Its surface is composed of water ice and is one of the smoothest in the Solar System. This surface is striated by cracks and streaks, while cratering is relatively infrequent. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably serve as an abode for extraterrestrial life.[12] This hypothesis proposes that heat energy from tidal flexing causes the ocean to remain liquid and drives geological activity similar to plate tectonics.[13]
The Galileo mission, launched in 1989, provided the bulk of current data on Europa. Although only fly-by missions have visited the moon, the intriguing characteristics of Europa have led to several ambitious exploration proposals. The next mission to Europa is the European Space Agency's Jupiter Icy Moon Explorer (JUICE), due to launch in 2022.[14]
Discovery and naming
Europa was discovered on January 8, 1610 by Galileo Galilei,[1] and possibly independently by Simon Marius. The moon is named after a Phoeniciannoblewoman in Greek mythology, Europa, who was courted by Zeus and became the queen of Crete.
Europa, along with Jupiter's three other largest moons, Io, Ganymede, and Callisto, was discovered by Galileo Galilei in January 1610. The first reported observation of Io was made by Galileo Galilei on January 7, 1610 using a 20x-power, refracting telescope