Authors and Resources
Orbiting the planet Jupiter are six known moons, of which the fourth largest is Europa. Europa is slightly smaller than the Earth’s moon, having a diameter of 3,138 kilometers. Europa is similar in bulk and composition to the terrestrial planets being, composed mostly of silicate rock. However, Europa’s surface isn’t like anything else in the inner solar system. It is an incredibly smooth layer of ice, which strongly resembles images on Earth of pack-ice on the polar seas during spring thaws. Few landforms exceed a few hundred meters in height, which makes Europa one of the smoothest objects in our solar system. The surface is a chilly –200 degrees Celsius. There are very few craters on Europa. Only three larger than five kilometers in diameter have been found. This would seem to indicate a young and active surface because cratering is viewed as an aging process. However, the precise age of Europa is still unknown.
Europa’s most striking aspect is the many dark streaks resembling broken panes of glass which crisscrossing the entire globe. The larger ones are approximately 20 kilometers across and may run for thousands of kilometers. The latest theory of their origin is that they are produced by a series of volcanic eruptions or geysers. Europa’s atmosphere is composed of oxygen. Unlike the oxygen in Earth’s atmosphere, Europa’s is almost certainly not of biologic origin. Instead it is most likely generated by sunlight and charged particles hitting Europa’s icy surface producing water vapor, which split into hydrogen and oxygen. The hydrogen then escaped leaving the oxygen. Europa is pulled in different directions by Jupiter and its other moons causing it to be alternately extended and compressed over the period of a day. Some scientists have suggested that heat is generated by this tidal flexing, which may be enough to melt the ice below the crust creating lakes or even oceans below the surface. The possibility of liquid water naturally leads to the question of whether life could have evolved there.
Movie
