An unexpectedly varied landscape of mountains and valleys, rivers and lakes - bathed in an alien orange light - emerged over the weekend as scientists began processing pictures and data taken by the Huygens space probe on its descent to the surface of Titan.

The European probe landed on Friday on what looked like a beach strewn with stones and pebbles after parachuting through Titan's thick nitrogen atmosphere. John Zarnecki of the UK Open University, lead researcher for the Huygens surface science package, said: "Two of the instruments recorded the impact and from those signatures it is looking like we landed on a surface that was neither hard solid nor liquid - something in between."