How can we prove alien life when they inevitably do show up? With a slew of new missions poised to return data from alien worlds, the pace of potential discoveries is likely to accelerate. So, what questions should we ask ourselves when apparent evidence of alien life inevitably arrives? We walk you through the most plausible ways it might first show up, from faint chemical signatures to fossilised microbes. Think of it as a scientific gut-check – a sliding scale of how close different scenarios

On Thursday, President Trump directed his administration to release files on UFOs and any "alien and extraterrestrial life," an issue that has drawn decades of public fascination and debates over if we are really alone out there. Dr. Erin Macdonald, who is the science advisor for Star Trek, explains the real science behind the headlines. "We have not confirmed any life outside of our own planet, either existing now or existing in the past, but the odds are great," she tells CBS News' Dave Malkof