Let there be light: How stars lit up the universe for the first time, now astronomers know a bit more

"Finding the impact of the first stars in that cacophony would be like trying to hear the flap of a hummingbird's wing from inside a hurricane," Kurczynski said in an NSF video.

Because the high end of the frequency they were looking in is the same as FM radio, the astronomers had to go to the Australian desert to escape interference. That was where they installed their antennas.

They then labored to confirm what they found, in part by testing it against dummy signals in the lab, and it all showed that what they spotted was the existence of the first stars, Bowman said.

So far, the scientists know little about these early stars. They were probably hotter and simpler than modern stars, Ellis and Bowman said. But now that astronomers know where and how to look, others will confirm this and learn more, Bowman said.

The research does not establish exactly when these stars turned on, except that at 180 million years after the Big Bang, they were on. Scientists had come up with many different time periods for when the first stars switched on, and 180 million years fits with current theory, said Ellis, a professor at University College London.

When this signal was found and examined, it showed that the hydrogen between stars was "even colder than the coldest we thought possible," said Rennan Barkana, a Tel Aviv University astrophysicist who wrote a companion study on the dark matter implications of the discovery. The researchers expected temperatures to be 10 degrees above absolute zero, but they were 5 degrees above absolute zero (minus 451 degrees Fahrenheit, or minus 268 degrees Celsius).

"The only thing we know from this signal is that something very weird is going on," Barkana said.

What seems likely is dark matter - which scientists have never seen interacting with anything - may be cooling that hydrogen, he said. Dark matter makes up about 27 percent of the universe, but scientists know little about it except that it's not made of normal matter particles called baryons.

Scientists have known dark matter exists, indirectly, through measurements based on gravity. If this interpretation of the data is correct, it would be the first confirmation of dark matter outside of gravity calculations, Barkana said.

It also potentially reveals something new about the nature of dark matter.

"If the result is correct it constitutes an indirect detection of dark matter and, moreover suggests something of fundamental importance (its interaction with baryons)," Johns Hopkins University astrophysicist Marc Kamionkowski, who wasn't part of the study, said in an email. "This therefore is about as important as you can get in cosmology."