NASA telescope sees oldest starlight ever found

By studying traces of ancient starlight, astronomers are gaining a better understanding of how the infant universe took shape — a step toward answering questions about the nature of space, time and energy as defined by Einstein's theories.

But the deeper in space that scientists probe, the murkier things become. Even with ever-improving technology, the oldest stars are still too distant to observe directly. In probing this and other enigmatic phenomena, astronomers often make assumptions based on what the latest instruments reveal.

"We don't have the telescopes now to see these stars. They're small and very far away, so we look for signatures from the light that came from them," said Alexander Kashlinsky, a cosmologist at the National Aeronautics and Space Administration's Goddard Space Flight Center in Greenbelt, Md.

Studying these light signatures, Kashlinsky and a team of researchers, using NASA's Spitzer Space Telescope, announced last week that measurements of infrared light from a far corner of the sky turned up what they say is the most ancient starlight ever found. The findings were published in a recent issue of the journal Nature.

The researchers analyzed ripples in ancient cosmic radiation — light invisible to the human eye — by filtering out light from closer and more recently developed stars.

Kashlinsky said the search was like sorting out the dimmest light bulbs among a vast field of bright and dim bulbs. The ancient stars have long since burned out, but large groups of them have left infrared signatures, he said. "What we observed was the emissions from superclusters that are made up of these stars."

Astronomers say the findings on ancient starlight open a window into a universe created by a cosmic explosion, known as the "big bang," that hurled matter in all directions. Initially, the explosion produced hydrogen and helium, but the universe remained in a fog for up to a billion years, a mysterious stretch known as the Cosmic Dark Ages.

The elements that made life possible, such as carbon and oxygen, came much later with the intense heat and gravitational forces produced by stars.

Astronomers are still unsure about how and when the earliest stars formed — an event called the Cosmic Dawn.

They say the light came from stars that were hundreds of times larger, thousands of times brighter and with much shorter life spans than any stars seen today.