Titan [TY-tun] is the largest moon of Saturn and the second largest moon in the solar system, rivaled only by Jupiter's moon Ganymede. Before the Voyager encounters, astronomers suspected that Titan might have an atmosphere. Scientists also believed they might find liquid seas or pools of methane or ethane; water would be frozen due to Titan's low surface temperature. Expecting an unusual world, Voyager 1 was programmed to take numerous close up views of Titan as it flew past in November of 1980. Unfortunately, all that was revealed was an impenetrable layer of atmosphere and clouds. Only slight color and brightness variations were observed.
Titan's surface temperature appears to be about -178°C (-289°F). Methane appears to be below its saturation pressure near Titan's surface; rivers and lakes of methane probably don't exist, in spite of the tantalizing analogy to water on Earth. On the other hand, scientists believe lakes of ethane exist that contain dissolved methane. Titan's methane, through continuing photochemistry, is converted to ethane, acetylene, ethylene, and (when combined with nitrogen) hydrogen cyanide. The last is an especially important molecule; it is a building block of amino acids.
Two potential signatures of life on Saturn's moon Titan have been found by the Cassini spacecraft. But scientists are quick to point out that non-biological chemical reactions could also be behind the observations.
Titan is much too cold to support liquid water on its surface, but some scientists have suggested that exotic life-forms could live in the lakes of liquid methane or ethane that dot the moon's surface.
In 2005, Chris McKay of NASA's Ames Research Center in Moffett Field and Heather R Smith of the International Space University in Strasbourg, France, calculated that such microbes could eke out an existence by breathing in hydrogen gas and eating the organic molecule acetylene, creating methane in the process.
The glow of Titan's extensive atmosphere shines in false colors in this view of Saturn's gas-enshrouded moon acquired by the Cassini spacecraft visual and infrared mapping spectrometer during the July 2, 2004, flyby.
While flying over the terminator, where Titan's day and night meet, both the dayside and night sides are seen at various wavelengths. In these views of the crescent moon, the sunlit side is on the left and the nightside on the right. The blue image shows the sunlit crescent as observed at a wavelength that pierces through the thick atmosphere to show only the surface. This image is much smaller than the other three images to the right, because it does not show any atmospheric affects.
In contrast, the green image shows the immense size of Titan's atmosphere. This is revealed by the fluorescent glow of methane gas, which extends over 700 kilometers (435 miles) above the surface, showing that the atmosphere nearly doubles the size of Titan. This glow is at a wavelength of 3.3 microns, five times the wavelength visible to the human eye.
The Titan have a lot of hydrocarbons under its surface. Scientists all over the world are certain that if an electric surge of 10,000KV or more, is sent into the underground reserves of titan at the same time, from all the directions. The reaction of the hydrocarbons would create a massive ocean of pure water on Titan and then may be the atmosphere of the titan would drop as well
