Scientists were thrilled last year when in June, Cassini spacecraft detected more than 75 lakes on the frozen Titan, one of Saturn's moons. Of course, at those temperatures, the lake could not have been formed of water (which would be frozen).

The lakes are in fact filled with methane, possibly even ethane, organic molecules which on Earth environments are gases, but they are liquid on Titan's extremely cold ambient. At -180° C, these chemicals, which are gases in Earth's conditions, behave like water, being transparent.

Titan is the only moon in the sun system which possesses a dense hazy atmosphere with thin layers of methane and nitrogen vapors, very similar to a primordial Earth.

Methane is sensitive to light and must constantly be renewed.

It's possible that lakes or even oceans of methane might exist on, or just beneath, the moon's surface and evaporation from these sources may fuel the atmosphere with methane. The lakes have been spotted on the moon's northern pole. Some lakes seem to be alimented by sinuous "rivers", some over 62 miles (100 kilometers) long.

Scientists think the lakes may increase in the winter hemisphere while those in the summer hemisphere should shrink or entirely vanish.

Now, researchers have found Titan's lake that seems to be slightly smaller than the Caspian Sea, the biggest lake on Earth. The 1100-kilometre-long lake seems to be the largest yet discovered on the moon.

The new images were taken on the 22nd of February, employing Cassini's Imaging Science Subsystem (ISS), which is comprised of two cameras that can see in ultraviolet, visible and infrared light. The new images have revealed yet more lakes, including one with a large island in its center. The island is 150 by 90 km (95 by 55 miles), about the size of the Big Island of Hawaii.