Astronomers have picked up a radio signal from the moment the lights went on in the universe billions of years ago, and they've discovered some surprises embedded in it. No, not aliens, but potential evidence of something just as mysterious and elusive. From a report: Using a sensitive antenna only about the size of a table in the Australian desert, scientists managed to isolate the very faint signal of primordial hydrogen, part of the cosmic afterglow from the Big Bang. But the ancient signal from this basic building block of the universe also carries the imprint of some of the first light from the very first stars ever. "This is the first real signal that stars are starting to form, and starting to affect the medium around them," Alan Rogers, a scientist at MIT's Haystack Observatory, said in a statement. "What's happening in this period is that some of the radiation from the very first stars is starting to allow hydrogen to be seen. It's causing hydrogen to start absorbing the background radiation, so you start seeing it in silhouette, at particular radio frequencies." Rogers is a co-author of a paper on the work published Wednesday in the journal Nature.