7 Ways We Might Finally Prove Aliens Exist

5. Biosignatures

Living beings are a leaky old bunch and one of the ways we might be able to detect their presence is by looking for the tell tale signs of life in their atmosphere.

A biosignature is a catch-all term for anything - gases, compounds, etc. - that might have been produced by life. These might be complex organic molecules or just fluctuating levels of methane in the atmosphere.

There are a couple of catches, however, chief of which being that you have to assess how likely it is that the farty atmosphere of the planet you're looking at is produced by, say, geological activity. This means assessing, not only how likely it is to be organic, but how unlikely it is to be inorganic.

Another problem is actually being able to see the damn things in the first place. NASA are planning on launching missions, perhaps as early as 2018, to scout out some potentially habitable "super-Earth" exoplanets for potential habitability.

If looking for alien farts isn't quite what you imagined for the glamour of space travel, then skip the next entry as we might just be going through their bins too.