In 1977, a volunteer scanning data from the Big Ear Radio Observatory in Ohio circled an unusually strong signal on a printout and wrote ‘WOW!’ next to it. The signal lasted 72 seconds and has never been detected again. For nearly half a century it has been held up as the most tantalising moment in the search for extraterrestrial intelligence. There's an irony, then, in the fact that by the UCLA team's own strict definition of what constitutes a genuinely technological signal, the ‘Wow!’ signal doesn't quite make the cut, its frequency spread is just broad enough to allow a natural origin. We are, it turns out, still waiting for the first confirmed one. The Wow! signal represented as "6EQUJ5" which articulates the signal strength (Credit : Big Ear Radio Observatory) A team at UCLA has been trying harder than most. For the past ten years, they have been using the Green Bank Telescope in West Virginia which is the largest fully steerable radio telescope on the planet, with a dish spanning 100 metres.…