The foggy dawn of the universe, a time even prior to the shining of stars, has been detected by astronomers conducting an extensive sky survey, it was reported this weekend.
The discovery of the "cosmic dark ages" reaches back to an epoch more than 12 billion years ago, after the Big Bang, when the universe's expanding hydrogen gas cooled and circulated through space in a huge, thick haze.
That haze is thought to have blocked light emitted by the universe's first stellar objects, as evidenced by a newly detected shadow seen in light from an extremely distant quasar, according to The New York Times. Quasars are some of the earliest star-like objects in the universe, burning with the energy of billions of Suns and difficult to detect as they are so far away.
"The expectation is that the universe started off, the first half-million years, being very hot," because of the initial explosion 13 billion years ago that birthed the universe, Sir Martin Rees, an astrophysicist at Cambridge University, told the newspaper.
As the universe cooled, it remained in darkness for hundreds of millions of years until stars started forming and ionized the gas, Rees said.
"And then the fog suddenly lifts, as it were," he said.
The quasar shadow effect, a result of follow-up research on a project called the Sloan Sky Survey, was like seeing clouds drift in front of the Moon, the newspaper said.
The findings will be submitted this week to The Astronomical Journal, said Princeton University astrophysicist Michael Strauss, who was among the project's leaders.
"We're in some sense probing the end of the dark ages, which means the universe has lit up," he said.
Other scientists involved in the finding were Xiaohui Fan of the Institute for Advanced Study in Princeton and Richard L. White of the Space Telescope Science Institute in Baltimore.
The Sloan Survey is an $80 million, five-year census of the cosmos in which scientists all over the world are participating. In the past few years, it has detected the four most distant objects ever found.
Those objects were combed out by astronomers intentionally, using the Sloan's telescope in Apache Peak, New Mexico. Then astronomers looked at them more closely with the Keck Telescope on Mauna Kea, in Hawaii. The light pattern emitted by the most distant object of the four showed the tell-tale swath, the presumed shadow of the cosmic dark ages.
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