Newsround Extra takes an in-depth look at the search for life in space.
Click on the links on this guide to find out more about Becky's investigation.
For years we Earthlings have wondered whether we are alone in the universe or whether we've got company in the shape of aliens.
People have claimed to have met aliens, seen UFOs - unidentified flying objects - and some people even say they've been abducted by extra terrestrials.
But what do we really know about them - if they exist at all?
Is there life on other planets?
