Peering Into The Cosmic Past

(AP)  Astronomers looking more than 13 billion light years across the universe have captured images from 800 million years after the big bang, when all stars and galaxies were fresh and young.

Using a highly sensitive camera on the Hubble Space Telescope, researchers from the Arizona State University and the University of Arizona gathered very faint ultraviolet images, little more than red blurs, of stellar objects that were formed and shining when the universe was about seven times smaller than it is now.

"With the Hubble Telescope, we can now see back to the epoch when stars in young galaxies began to shine in significant numbers, concluding the cosmic dark ages about 13 billion years ago," said Haojing Yan, an Arizona State astronomer. He presented data from the studies on Thursday at the national meeting of the American Astronomical Society.

"The objects we sighted are less luminous than our Milky Way," said Yan. "There are very few big ones and more fainter ones."

According to theory, the universe started with a gigantic explosion - the big bang - about 14 billion years ago. Then, it contained only superheated hydrogen and helium atoms, with no stars.

Within a few hundred million years, the atoms cooled and irregularities in the texture of the universe caused clumping. Eventually bodies gathered enough material to compress the hydrogen and ignite the nuclear fires burning at the cores of young stars.

Theorists believe it took about a billion years for enough stars and galaxies to form to end the cosmic dark age.

"The observations are pushing back the frontiers of what we know about the early universe," said C. Meg Urry, a Yale University astronomer not associated with the team that released the findings.

The Hubble study found 30 very faint galaxies. Yan and other astronomers estimate that there were at least 400 million such objects in the universe at that time.

"What we have discovered is likely only the tip of the iceberg," said Rogier Windhorst, an Arizona State astronomer and a member of the team that did the study.

Windhorst said that space telescopes now being designed for launch likely will "find the entire iceburg," pushing back even farther the time when galaxies may have existed.

Among the objects are three quasars, which are compact, bright objects powered by super-massive black holes.

The images come from only a small field of view in the constellation Virgo. This area was selected because it contains few nearby bright stars that would obscure the attempt.

A light year is the distance light travels in one year, about 5.8 trillion miles.