Two Halves of Titan, 2009 NASA/JPL/Space Science Institute
Saturn has dozens of moons, but Titan stands out from the pack. It is Saturn's biggest moon and the second largest in our solar system (The biggest is Jupiter's Ganymede.) Not only is Titan bigger than our moon, it is bigger than the planet Mercury. Titan was first discovered by the Dutch astronomer Christiaan Huygens on March 25th, 1655. As the anniversary of this date approaches, it's a wonderful time to learn more about this mysterious and unique moon.
Huygens Probe and Titan by Craig Attebery
For years, Titan remained a mystery. It has a thick atmosphere of nitrogen, methane, and ethane that hid its surface from cameras for years. It is the only moon in our solar system that is known to have a planet-like atmosphere, and it may even resemble Earth's atmosphere in primordial times. In 1997 the Cassini launched with the Huygens probe. In 2005 the Huygens Probe landed on Titan, seeing the surface for the first time. Since then our knowledge of Titan has grown immensely. Data collected by Cassini sugest the presence of an underground ocean on Titan. Titan even appears to change according to seasons and time of day. It may also look younger than it really is because its craters are slowly being filled in.
Moons Small to Large, 2011 NASA/JPL/Space Science Institute
If you would like to learn more about Titan, Saturn, or the Cassini-Huygens Mission NASA's website has the lastest, up-to-date information as well as gorgeous images and videos to browse. You can also watch the TED talk from 2007 by the leader of the Imaging Team on the Cassini mission below.