Madsen Pirie

I love it that we can take photographs of things like this.  As a boy I used to look through my homemade telescope at Saturn.  On clear nights I could see the rings, and Titan.  Sometimes I thought I could make out the faint light of maybe another two.  Titan was discovered by Chrstopher Huyghens in 1655, and Enceladus by William Herschel in 1789.  They are charismatic for different reasons.  Titan is the solar system’s second largest satellite, being larger than the planet Mercury.  Its dense, opaque atmosphere long hid its surface, but we knew it was rich in hydrocarbons, and speculated on methane lakes and geysers of ammonia mixed with water.  The Cassini-Huygens lander mission of 2004 showed us surface topography with inlets and outcrops.  Titan is the larger, faint, distant moon in the photo.

Enceladus, like Jupier’s Europa, is believed to have large quantities of subsurface water, with cryovolcanoes shooting huge geysers into space.  Some falls back, while others add to the ice particles in Saturn’s rings.  We know that Enceladus is geologically active, and believe that tidal heating of the interior is behind this.  It all makes Enceladus quite a reasonable bet for the discovery of alien life, and future missions will undoubtedly explore this.  Some of the most exciting pictures of the future will be from probes sent into the subsurface waters with lights and cameras to see what swims in those seas.  Until then, sit back and enjoy the present view.  You can just about make out some of the characteristic tiger striping on smaller Enceladus in the foreground of the shot.  Cassini was about 1m km distant from it when this image was taken.

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