If you sent a message to an alien civilisation, what would it be? It's a serious question currently being debated by scientists. Listening out has brought no response; now they say it's time to seek them out, considering there's every chance someone's out there. | BBC World Service

Astrophysicists in Russia examine unidentified radio emissions which lead to the conclusion that alien civilizations exist and are millions of years ahead of us. | Ancient Aliens: Out of This World Moments