While the idea of alien life might sound like science fiction,
it's becoming more and more of an established scientific theory.
And in the next few years, I believe it will become a scientific fact.
The field of astrobiology is now well established,
and it started off by looking at possible signs of fossilized life
in meteorites that have fallen to Earth.
In fact, there's a theory called Panspermia that says life exists throughout the universe
and transports from one place to the other via asteroids, comets, and meteors.
Now, as beautiful as the Earth is to us human beings,
in the grand scheme of the universe it's actually nothing special.
And hence if life can exist here, there's no reason it can't exist elsewhere in the universe.
In fact, it may exist in our own backyard in our own solar system.
We just need to find it.
While alien life may take many different exotic forms,
the easiest way to search for it is to look for conditions
like where it already exists. And this means finding liquid water.
Now, the way scientists do this is to search for a region called the Goldilocks zone around a star.
Too close to a star and water boils and turns to steam, and so life can't exist.
Too far away and the water turns to ice.
But in this middle region it's just perfect, and liquid water exists.
This immediately gives us a number of candidates, one of which being Mars.
The pieces of the puzzle are starting to come together.
In September 2015, liquid water was found on the surface of Mars.
And even more interestingly is that methane has been discovered present in the atmosphere.
So why is this exciting? Well, methane is actually a waste product
that's created by living organisms, us included.
So if methane is present on Mars, there's a tantalizing prospect
that it could be being created by living organisms.
So when I'm talking about alien life, I'm talking about microbes rather than little green men.
Further research needs to be conducted, but if there is life on Mars
where else could it exist? Another great prospect
is a moon of Jupiter called Europa.
It's believed that below its massive surface there could be a vast liquid ocean
kept warm by geological activity.
In fact, Europa is such a good prospect for life
that both the European Space Agency and NASA are sending probes there to investigate it.
So where does this leave our little green men?
Well, scientists aren't actually discounting them.
The Search for Extraterrestrial Intelligence Program
has been going for over three decades now looking for signs of alien life.
And the Chinese government is taking this so seriously
that they've built the world's largest radio telescope
looking for signals coming from alien civilizations.
However, if they were to detect any signals coming from these aliens,
the vast distances between us will make it impossible for us
to ever have meaningful communication.