Astronomers using the Hubble Space Telescope have peered 13 billion years back into time, almost to the dawn of creation, to find the oldest, most distant object ever detected: a galaxy fizzing with new stars.
The galaxy lies near the edge of the universe, 13 billion light-years from Earth, where its presence was detected by its faint ultraviolet light, which is invisible to conventional telescopes.
Paradoxically, the oldest known galaxy, dubbed "Sharon" after the sister of one of its discoverers, appears young to us.
That's because the deeper astronomers look into space, the further back in time they are looking. It takes so long for light traveling through space to reach Earth that astronomers scanning the edges of the universe are seeing objects as they were billions of years ago.
By some estimates, we are seeing the galaxy as it existed 1 billion years after the Big Bang, the colossal explosion believed to have created the universe.
The discovery by researchers at the State University of New York at Stony Brook was reported in Thursday's issue of the journal Nature.
It marks the third time in the past year that astronomers have found what were thought to be the most distant objects yet.
Other astronomers said the finding can help them determine when galaxies formed and developed, and learn more about the origins of the chemical elements that make life possible.
"Finding the most distant galaxies is akin to finding the oldest fossils on Earth," said Patrick McCarthy of the Carnegie Institution Observatories in Pasadena, Calif. "They give you a handle on the timing and processes by which the first recognizable galaxies coalesced from the primordial sea of light elements."
Galaxies appear to come in two basic designs: disc-shaped spiral galaxies like the Milky Way, and more massive, elliptical galaxies. But the SUNY researchers said their target is much too far away even for the Hubble to see clearly, so they can't say what type it might be.
"It's really not interesting to look at," said Kenneth Lanzetta, co-author of the Nature study. "There is no detail to be seen."
In fact, the new galaxy is so faint that some astronomers said they might have to wait until better instruments are developed to learn something from it. Richard Green of the Kitt Peak National Observatory in Tucson, Ariz., said the discovery is "at the limit of our grasp."
Until recently, records for the most distant objects in space stood for years. But sensitive detectors on the Hubble and large ground-based telescopes are capturing the faintest light from the most distant neighborhoods of the cosmos, and the record books are being rewritten every few months.
By Joseph B. Verrengia