4. Enceladus - Spectacular Ice Plumes
"The discovery of Enceladus' icy jets and their role in creating Saturn's E-ring is one of the top findings of the Cassini mission to Saturn. Further Cassini mission discoveries revealed strong evidence of a global ocean and the first signs of potential hydrothermal activity beyond Earth making this tiny Saturnian moon one of the leading locations in the search for possible life beyond Earth."