Did you know that at the moment there is a robot on Mars called the curiosity Rover? It’s looking for signs that life might have existed in the past. It’s been on Mars for a while now, but just last week it found evidence that in the past there was pure water, which you are I would probably have been able to drink safely! They think this means that Mars might have been able to support life in the past (but not now, as there is no water there any more), but they haven’t found any evidence of past life forms there yet…my fingers are crossed that they find out something lived there once. It would be an amazing result!
I’m not sure about which planet, like Nicola says there might have been life on Mars previously. Scientists think though that we might be able to find life on one of the moons of one of the bigger planets. The most likely candidate is Titan which is a moon of Saturn. It’s much colder there than on Earth so it doesn’t have liquid water at the surface, but it does have other liquids and it might have liquid water under the surface. If we were to find life there it would probably be quite different to the type of life that you find on Earth, but I think its possible. Titan has a thick atmosphere which is something that is probably needed for life to start as well as liquids, so it does look quite promising.