We have been hearing so much about aliens that a close encounter may well be possible this century, says a leading scientist urging governments to be prepared for the eventuality.
Jocelyn Bell Burnell, physicist and Oxford University professor, told the Euroscience Open Forum conference in Dublin: "I do suspect we are going to get signs of life elsewhere, maybe even intelligent life, within the next century."
Burnell said we are most likely to find alien life where we find rocky planets with carbon dioxide and ozone in the atmospheres. "If we do suspect there is intelligent life out there, are we going to make ourselves known to them or not?"
"There are interesting questions about who you would tell first - the press, the prime minister, the pope? We should start thinking now," said Burnell. However, she said that even if we do find signs of alien life, it is likely to take decades to talk to them from Earth via radio or lasers, the Daily Mail reports.
Burnell said: "Nothing can travel faster than the speed of light. So you are probably talking of conversations that could take 50 or 100 years, just one way."
Previous research has found almost half of Britons believe in little green men. The poll of more than 2,000 men and women for the Royal Society found that 44 percent are of the opinion extra-terrestrial life exists and more than a third of those questioned said we should be actively searching and trying to make contact with ET.
Some say that if we alert hostile aliens to our existence we risk an invasion that could lead to the end of life on Earth. They argue that if ET has the technology to cross space to reach us any defences we have will be all but useless. And Stephen Hawking has warned that aliens may plunder Earth for its resources.