Question: is there life on mars or any other planet?

Mark Lancaster answered on 13 Jun 2010:

There is not life on Mars at the moment (well not on the surface, there may be some primitive micro-organisms deeper inside where it is warmer) but in all likelihood there was in the past when it was warmer. There is increasing evidence that water must have flowed on Mars and it has a similar chemical make-up to the earth and also has an, albeit thin, atmosphere so given this there probably was life until the planet got too cold to sustain it. I’d say there is almost certainly life on other planets just from a probability point of view – there are at least 100 billion galaxies and in each galaxy typically a 100 billion stars many of which (10% or so) are surrounded by planets. You can then define the criteria for life: starting from the star the planet is orbiting – the star must burn light elements to heavy ones; to the planet’s composition: it should be solid and its location: right distance from the star to allow liquid water to form e.g. in our solar system Venus is just slightly too close (and so too hot) to the sun and Mars slightly too far (and so too cold) and with these criteria work out the odds that one of these (thousand billion billion) planets satisfies these conditions and while this is not an exact probabilistic determination the odds are certainly in favour… (we still don’t know having got the conditions for life: water the right elements, light from the sun how life itself actually started ie how we got from the right atoms to self replicating DNA). Personally I don’t think we are “special” in any way – there could well be advanced lifeforms out there who got bored of the internet billions of years ago !