The search is taking us deeper into space.
So far, more than 100 planets have been spotted among these stars - although none of them look like a good place to find aliens.
Beagle 2 was the first British-led mission to Mars. It was supposed to be looking for signs of aliens.
The Beagle probe should have landed on Mars in 2003, but vanished without a trace.
It's thought Beagle went wrong because Mars' atmosphere was thinner than expected, meaning it didn't slow down enough for a safe landing.
But if there are any aliens out there, a space program called SETI - Search for Extra Terrestrial Intelligence - hopes to be the first to know using telescopes.
Our chances of picking up signs of aliens are about to improve - SETI is building 350 new telescopes to scan more stars than ever.