This tour is a detailed look at the evidence proposed for the existence of such a subterranean ocean. We will expand on ideas, terms, and expressions used by geologists to describe the surface which were first introduced in the Exploratour in the Surface of Europa, so you may want to first take that tour. It can be linked to from the bottom of this page.
There are 9 points to consider. Some of them are shown in the collage. They are: craters, pits domes & spots, cryovolcanism, pull apart features, chaos, ridges, frost on surface, global linea, overall topography. Scientists trying to understand what these bits of evidence from the surface are saying about the possibility of an ocean is a bit like a detective studying the scene of a crime. It may take many years before scientists are able to fit all the pieces of evidence together such that they draw the correct conclusion. The 9 pieces of evidence can be explained with the existence of an ocean, but scientists can also show that an ocean is not necessary to explain the 9 pieces of evidence.
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