There may have been much ado on Charon, Pluto's largest moon, a very long time ago.
Scientists believe there are cracks on Charon's icy surface, an indicator that its interior may once have been warm enough to support an ocean. It is already believed Charon's surface consists of water-generated ice.
There is precedence for this. Both Saturn and Jupiter have moons, Enceladus and Europa respectively have underground oceans and the model seems to fit for Charon's past.
The cracks in Charon's surface may have been generated by a period in which Charon may have experienced an erratic orbit around Pluto. This type of non-linear orbit would have created tidal forces, creating friction that warmed Charon's interior and caused the surface cracks.
Charon is about half of Pluto's size, and its orbit around Pluto matches Pluto's rotation time. That means that Charon remains stationed over the same patch of Pluto's surface, a condition called tidal locking. Charon was named after a demon in Greek mythology, whose purpose in life was to transport souls to the underworld.
Next year, we may find out if Charon, was, or is maintaining a liquid ocean beneath its surface. NASA's New Horizons mission is on track to reach Pluto and its moons in July 2015.
New Horizons will be only the fifth spacecraft to fly at least as far as Pluto, which is approximately three billion miles from Earth. Its surface temperature is thought to be -380 degree Fahrenheit, which is of course far too cold to support water in liquid form. As of 2006, Pluto is no longer considered worthy of being called a planet, despite the fact that it has five moons in its orbit.
The most recent moon was discovered in 2012 via the Hubble Space Telescope, and carries the emotionally charged moniker P4. For the record, because Pluto does not meet all three currently defined rules for planetary status (must orbit the Sun; must have enough mass to be round; must be able to repel debris and rock from their orbits), it is referred to as a dwarf planet.
Ironically, the presence of at least five moons (there may yet be more) could present a collision hazard for New Horizons; NASA engineers are continually tweaking New Horizons flight path to prevent this from happening.
New Horizons will attempt to determine if Pluto has or had volcanic activity; it will also analyze the visual differences between Charon and Pluto, and seek reasons why Pluto has an atmosphere while Charon does not.
