Moon o' Lakes (Saturn's Moon Titan)

Titan, the largest of Saturn's at least 62 moons, has intrigued scientists for years, largely due to the many similarities that Titan shares with Earth. Over the last 20 years, scientists have speculated about lakes made of liquid hydrocarbons on Titan's surface. While no large seas have been indicated by data received from Cassini, what appear to be many large lakes near both the north and the south poles have been revealed.

The only known moon in the solar system larger than Titan is Ganymede, one of the many moons of Jupiter. The diameter of Titan is roughly one and a half times that of Earth's moon. Although less in mass than Mercury, Titan is larger in volume.

The Cassini spacecraft began its orbit of Saturn in 2004. Until 2009, the northern hemisphere of Titan was unseen by Cassini, being covered by the darkness of winter. Saturn's rotation around the sun is equivalent to 29 1/2 Earth years. Upon the change of the seasons and with the return of light, Cassini captured this image: reflected sunlight from one of Titan's lakes near Saturn's northern pole.

"This one image communicates so much about Titan -- a thick atmosphere, surface lakes and an otherworldliness," says Bob Pappalardo, Cassini project scientist, based at NASA's Jet Propulsion Laboratory. "It's an unsettling combination of strangeness yet similarity to Earth. This picture is one of Cassini's iconic images."

Cassini scientists were able to confirm the presence of liquid in Titan's largest lake in the Southern Hemisphere, Ontario Lacus, in 2008. Although encouraging, scientists still wanted very much to prove the existence of liquid in the Northern Hemisphere, which has larger basins outnumbering those in the Southern Hemisphere. While processing the original image from Cassini on July 10, 2009, Katrin Stephan was the first to see what is called a glint, also referred to as a specular reflection.

Cassini continues to explore Titan. Its last flyby, dubbed "T66", was on January 28th. Cassini took almost seven years to reach Saturn. The unmanned probe reached Saturn in 2004 with the mission due to end in 2008. NASA has stated that the exploration of the Saturn system will last until 2017. Hopefully, we will continue learning all about the wonders of Saturn and Titan for many more years to come.

Methane lakes dotting the surface of Titan's Northern Hemisphere