8 Things You Need To Know About NASA Finding Water On Mars

Really, the idea that we've discovered that Mars has running water is a bit of a misnomer. Basically, what we've discovered is that Mars still has running water.

We already know that Mars had liquid water, not to mention a water cycle, a few billion years ago.

Ancient Mars was a warm, wet planet. We're now pretty sure that, once upon a time, Mars had vast oceans and powerful rivers carving up the landscape - the effects of which we can still see today.

At that time, Mars would have also had an atmosphere, perhaps not unlike Earth's, but unfortunately the little red planet just couldn't keep a hold of it. Due to Mar's smaller size, and therefore weaker gravity, the atmosphere was much more vulnerable to being lost into the vacuum of space. 

The loss of the atmosphere over time caused a drop in atmospheric pressure. The effect of this was two-fold: firstly it would lower the boiling point of all that lovely water on its surface, secondly, it would mean that global temperatures would have dropped, freezing the remaining water solid.

This also leads us on to an important point about life on Mars...