Rainstorms as intense as any on Earth pound the surface of Saturn's giant moon Titan (left) , research revealed yesterday. But the alien Titan weather is like nothing we are used to.

The rain is made of liquid methane and forms droplets 5mm wide that crash to the ground at more than 100 kilometres per hour (64mph).

A new model of Titan's atmosphere predicts fierce storms generated by thick hydrocarbon clouds that cluster around the moon's south pole.

The cloud bursts are thought to be responsible for some of the dramatic features seen on Titan's surface, such as the mean-dering river channels and lake beds pictured by Nasa's Cassini spacecraft. Icy round boulders and cobblestones have also been seen that look as if they were shaped by flowing liquid.

The rainstorm model w as produced by Dr Ricardo Hueso and Dr Agustin Sanchez-Lavega from the University of Pais Vasco in Bilbao, Spain.

It suggests that the strongest storms occur when methane humidity in the middle atmosphere tops 80 per cent. This could generate updrafts as fast as 72 kilometres per hour (45mph) to create thick clouds as high as 30 kilo-metres (18.6 miles).

Rain could dump up to 110kg (242lbs) of liquid methane on each square metre of ground.