UFOs - What do we know?

Dr Chris Smith and the Naked Scientist team present the latest science news, analysis and breakthroughs.In today's programme: As NASA meet to investigate U-F-O’s and whistle-blowers claim countries have been stashing alien spacecraft for decades, we’ll be asking what do we know about Unidentified Flying Objects?Plus we ask how solar power stations in space would work? And we find out more about the fish that fight infection by swimming to warmer waters.Get the podcast from the BBC Sounds app.