It's one of the great unanswered questions......are we alone or is there life elsewhere in the universe?
Well it's been a big day today for the many people who think aliens DO exist - as the Government released its files on reports of UFOs for the final time.
The files contain a letter from a child in Altrincham asking the Prime Minister if he believes in life beyond earth.
Our correspondent Andy Bonner's been looking at the files and talking to an expert.
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