Astronomers Say They’ve Found Oldest Galaxy Yet

BY Jenny Marder  January 27, 2011 at 9:48 AM EST

Hubble has peered back into the far-ancient past and spotted a tiny galaxy of blue stars, possibly the oldest ever seen, researchers reported in the journal Nature. In images, it’s underwhelming – just a faint smudge of light.

But we’re seeing light from 13.2 billion years ago, scientists say. That’s how long the light emitted took to reach us. For perspective, the universe is only 13.7 billion years old, so this reaches back to the first 4% of its lifetime.

The galaxy’s name reads like a bar code: UDFj-39546284. And little is known about it, other than, it’s there, and it’s old.

“This galaxy, from 500 million years after the Big Bang, is extraordinarily faint, a very blue dynamic object, and full of stars forming star births,” said Garth Illingworth of University of California, Santa Cruz and co-author of this paper.


The data was found using the Wide Angle 3 camera, installed in 2009. Because the image is too far to be seen with ground-based telescopes, data will need to be confirmed by similar findings, scientists say, or with the more powerful James Webb Space Telescope, which is scheduled to launch in 2015.

During the time of the finding, the birth rate of stars was speeding up rapidly, possibly an indication of a new transition phase of star formation, said astrophysicist Rachel Somerville.

Peak star birth in the universe occurred 10 billion years ago, Illingworth said. “Since the last half life of the universe, star birth rate has been dropping distinctly and dramatically. We’re in a very quiescent time of the universe now…It’s sort of like we’re aging and nothing is happening.”

Capturing images of the formation of the first stars and galaxies, from the moments just after the Big Bang, is a sort of holy grail for astrophysicists. This discovery brings them a step closer to that. “We’re really pushing Hubble to its limits here,” Illingworth said. We can try and get more data, look for more of these 500 million year old galaxies, but we won’t be able to go to earlier times.”

For that too, they’ll need the James Webb Space Telescope.

Correction: An earlier version of this article said the earth is 13.7 billion years old. The earth is believed to be 4.5 billion years old.