TITAN (TIE-TUN)

One moon orbits our planet Earth. Saturn has the most moons in our solar system. So far, 62 moons have been discovered in Saturn's orbit, and 53 of them have been officially named.ne moon orbits our planet Earth. Saturn has the most moons in our solar system. So far, 62 moons have been discovered in Saturn's orbit, and 53 of them have been officially named. 


In many respects Saturn's largest moon, Titan, is one of the most Earth-like worlds we have found to date. With its thick atmosphere and organic-rich chemistry, Titan resembles a frozen version of Earth, several billion years ago, before life began pumping oxygen into our atmosphere.

Titan is of great interest to scientists because it has a substantial, active atmosphere and complex, Earth-like processes that shape its surface. The moon is enveloped by an orange haze of naturally produced photochemical smog that frustratingly obscured its surface.

Titan's surface is shaped by rivers and lakes of liquid ethane and methane (the main component of natural gas), which forms clouds and occasionally rains from the sky as water does on Earth. Winds sculpt vast regions of dark, hydrocarbon-rich dunes that girdle the moon's equator and low latitudes. Volcanism may occur as well, but with liquid water as the lava.

On its journey to Saturn, Cassini carried the European-built Huygens probe. On Jan. 14, 2005, Huygens achieved humankind's first landing on a body in the Outer Solar System when it parachuted through Titan's murky skies. Huygens took measurements of atmospheric composition and wind speeds during its decent, along with an incredible series of images showing telltale patterns of erosion by flowing liquid. The probe came to rest on what appeared to be a floodplain, surrounded by rounded cobbles of water ice.

As the Cassini Equinox Mission progresses, the spacecraft will monitor Titan's atmosphere and surface for signs of seasonal change. The spacecraft's radar and camera systems will continue to peer through the haze, expanding our high resolution maps of the surface. And scientists will eagerly await new data that could confirm the presence of a liquid ocean beneath the giant moon's surface.

The exploration of this amazing place is just beginning. Frigid and alien, yet also remarkably similar to our own planet, Titan is a new world – revealed before our very eyes by the Cassini and Huygens spacecraft.

Scientists report definitive evidence of the presence of lakes filled with liquid methane on Saturn's moon Titan.

• Based on the lake characteristics, Cassini scientists think they are observing liquid-filled lakes on Titan today. Another possibility is that these depressions and channels formed in the past and have now been filled by a low-density deposit that is darker than any observed elsewhere on Titan. However, the absence of wind-blown features in this area makes the low-density hypothesis unlikely.
• These northern hemisphere lakes are the strongest evidence yet that Titan's surface and atmosphere have an active hydrological cycle, though with a condensable liquid other than water. In this cycle, lakes are filled through methane rainfall or intersect with a subsurface layer saturated with liquid methane.
• As Titan's seasons progress over the 29-year cycle of Saturn's orbit around the sun, lakes in the winter hemisphere should expand by steady methane rain, while summer hemisphere lakes shrink or dry up entirely.

RECENT DISCOVERIES (as of Dec 12 2010)
When Cassini arrived in 2004, Saturn's northern hemisphere had a different look than when NASA's Voyager spacecraft flew by the planet in 1980. When Voyager visited, it was near the time of equinox, with ring shadows only across the equator and golden-hued clouds covering the planet. When Cassini got to Saturn, ring shadows draped across the northern hemisphere, whichappeared bluish, much like the deep, clear atmospheres of Uranus and Neptune. Scientists say that the ring shadows probably cooled the atmosphere down in the north, so golden and tan-colored clouds, visible in the Voyager images, sink to depths where they are no longer visible. (See Cassini Spacecraft Witnesses Saturn's Blues.)


Saturn has powerful lightning storms, 10,000 times stronger than on Earth, that occur in huge, deep thunderstorms columns nearly as large as the entire Earth. The storms occasionally burst through to the planet's visible cloud tops.


Saturn's auroras vary from day to day as on Earth, but rather than last a few minutes as on Earth, they can continue for days. The Sun's magnetic field and solar wind may have more to do with the aurora than previously believed.