Astronomers are finally able to present a solution to a mystery: how the cosmic fog from the early universe cleared. The culprit? Massive stars that emitted high energy light.

In a study published in the Astrophysical Journal Letters, lead author Jordan Zastrow of the University of Michigan proposes that blazing stars cleared the dense fog that surrounded the galaxy during its earliest days. In that distant era, the space between galaxies had been enveloped in a thick, opaque fog. How that fog dissipated into the transparent plasma we see today has always baffled scientists. Now, new evidence points to the early stars providing enough light to clear the fog.

Zastrow and her colleagues observed a dwarf starburst galaxy known as NGC 5253 using special filters that can analyze the light escaping from the galaxy. NGC 5253, which lies about 11 million light years away in the constellation Centaurus, isn't as old as the galaxies that provided the light that cleared the ancient cosmic fog, but it does show astronomers the phenomenon that was responsible for that event.

Starburst galaxies are galaxies that are in the process of a high rate of star formation. Although they are rare, there would have been enough of them in the early days of the universe.

"This galaxy is nearby, but we're trying to use it to better understand what was going on in the early universe," said Zastrow in a statement to MSNBC.

Using special filters in the Magellan telescopes, Zastrow and her team were able to observe the extreme ultraviolet radiation escaping from the starburst galaxy. This leaking radiation caused hydrogen gas near the galaxy to dissipate.

"We are not directly seeing the ultraviolet light," Zastrow said in a news release. "We are seeing its signature in the gas around the galaxy."

Superwinds from the galaxy's massive stars helped clear the gas within the galaxy and this helped the light to leak through. Normally the gas would have absorbed the galaxy's radiation but with the winds from the massive stars, the light was allowed to pass through.

"The opening that is letting the UV light out is very small, which makes this light challenging to detect," Zastrow said. "We can think of it as a lighthouse. If the lamp is pointed toward you, you can see the light. If it's pointed away from you, you can't see it. We believe the orientation of the galaxy is important as to whether we can detect escaping UV radiation."

The study's hypothesis about how the cosmic fog cleared could help other astronomers build a more accurate picture of the early universe.

"Particularly because this issue is so interesting, and so important for our cosmic history, the important thing is to better understand what is actually possible in terms of learning how it could have happened," Zastrow said.