Europa: Facts About Jupiter's Icy Moon and Its Ocean

Europa is one of the Galilean moons of Jupiter, along with Io, Ganymede and Callisto. Astronomer Galileo Galilei gets the credit for discovering these moons, among the largest in the solar system. Europa is the smallest of the four but it is one of the more intriguing satellites.

The surface of Europa is frozen, covered with a layer of ice, but scientists think there is an ocean beneath the surface. The icy surface also makes the moon one of the most reflective in the solar system. Researchers using the Hubble Space Telescope spotted a possible water plume jetting from Europa's south polar region in 2012. A different research team, after repeated attempts to confirm the observations, saw apparent plumes in 2014 and 2016. The researchers cautioned that the plumes haven't yet been fully confirmed, but they do provide a suggestion that there is water in Europa's ocean jetting to the surface.Several spacecraft have done flybys of Europa (including Pioneers 10 and 11 and Voyagers 1 and 2 in the 1970s). The Galileo spacecraft did a long-term mission at Jupiter and its moons between 1995 and 2003. Both NASA and the European Space Agency plan missions to Europa and other moons that would leave Earth in the 2020s. Distance from Jupiter: Europa is Jupiter's sixth satellite. Its orbital distance from Jupiter is 414,000 miles (670,900 km). It takes Europa three and a half Age: Europa is estimated to be about 4.5 billion years old, about the same age of Jupiter.Earth-days to orbit Jupiter. Europa is tidally locked, so the same side faces Jupiter at all times.Size: Europa is 1,900 miles (3,100 km) in diameter, making it smaller than Earth's moon, but larger than Pluto. It is the smallest of the Galilean moons.Temperature: Europa's surface temperature at the equator never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius). At the poles of the moon, the temperature never rises above minus 370 F (minus 220 C).