BACKGROUND: Using a telescope as a time machine, scientists at NASA's Goddard Space Flight Center are closer to identifying the first objects of the universe. The latest observations from the Spitzer Space Telescope suggest that infrared light detected in a prior study comes from clusters of bright objects that lived within the first billion years after the Big Bang.
THE DARK AGE: According to current science, space, time and matter originated 13.7 billion years ago in a tremendous explosion called the Big Bang. A few hundred million years later, the first stars formed, ending the "dark age" of the universe. Astronomers believe the objects observed by the Spitzer telescope are either the first stars --hundreds of times more massive than our sun -- or voracious black holes that are consuming gas and spilling out tons of energy. If they turn out to be stars, then the clusters might be the first mini-galaxies. Our own Milky Way was probably created when mini-galaxies like these merged.
IN THE INFRARED: The Spitzer scientists were looking specifically at the cosmic infrared background of the universe, a diffuse light from the early epoch when structure first emerged in the cosmos. A prior study reported in 2005 detected infrared light, suggesting that it originated from clumps of the very first objects in the universe. This second analysis indicates that this patchy light is scattered across the entire sky and comes from clusters of bright, monstrous objects more than 13 billion light-years away. Although that light began its journey as ultraviolet or visible light, by the time it reached earth, its wavelengths had been stretched into the infrared by the growing space-time that causes the universe's expansion. Based on the strength of the infrared light signal, they concluded that the total amount of energy produced by the objects was so large, only very large stars or black holes consuming a lot of matter would be capable of emitting it. Other parts of the cosmic infrared background are from distant starlight absorbed by dust and re-emitted as infrared light.
SEEING IS BELIEVING: When we peer into space with a telescope, we are actually looking back in time. Telescopes detect emitted light, and the light that reaches us from the closest galaxy, Andromeda, for instance, has taken two million years to reach us. The Spitzer telescope looked at the first brilliant objects to exist in our universe. The Spitzer telescope scanned five areas of the sky for about 25 hours per region, collecting light even from the faintest of objects. Then astronomers meticulously subtracted light from things that were in the way, such as foreground galaxies and dust in our solar system, or in interstellar clouds. When all that was left was the most ancient light, the scientists studied fluctuations in the intensity of the infrared brightness, revealing a clustering of objects to produce the observed light pattern.
The American Astronomical Society contributed to the information contained in the TV portion of this report. ON THE WEB: www.spitzer.caltech.edu/Media/releases/ssc2006-22 Podcast: www.spitzer.caltech.edu/features/podcasts/files/20061218Spitzer.mp3