Europa (Jupiter II)
Europâ, orupâ (#)
The sixth of → Jupiter's known moons and the fourth largest; it is the second of the → Galilean satellites. With a diameter of 3140 km, Europa is slightly smaller than Earth's Moon. Its mass is 4.80 × 1022 kg, i.e. 1.5 times less massive than Earth Moon. Its distance to Jupiter is 670,900 km, or about 9 Jovian radii. Its → orbital period is 3.55 Earth days which equals its → rotation period. Europa's density is 3.0 g cm-3, typical of a mixture of rocks including → ice. Its high → albedo (0.67) suggests that its surface is mostly → water ice. The → surface temperature of Europa ranges between about 125 K (-150 °C) at the equator and about 50 K (-220 °C) at the poles. There are few → impact craters on Europa, because its surface is too active and therefore young. The most striking features of Europa's surface are structures called → lineae and → lenticulae. The thickness of the ice crust could range between a few kilometers to a few tens of kilometers. It is now believed that there is an ocean of salty water, up to 100 km deep, flowing under Europa's ice. Europa's ocean is kept liquid due to → tidal heating by Jupiter.
In Gk. mythology, Europa was a Phoenician princess (Agenor's daughter) abducted to Crete by Zeus, who had assumed the form of a white bull, and by him the mother of Minos, Sarpedon, and Rhadamanthys.