Telescope spots oldest galaxy ever seen
US and European researchers trying to peer back to the beginnings of the universe said on Wednesday they have spotted what they think is the most ancient galaxy ever seen — 13.2 billion years old.
The aging Hubble Space Telescope collected light from the dim object, which would have formed when the universe was just 480 million years old, the researchers report in the journal Nature.
“We’re peering into an era where big changes are afoot,” said Garth Illingworth of the University of California at Santa Cruz, one of the researchers working on the study.
“The rapid rate at which the star birth is changing tells us if we go a little further back in time we’re going to see even more dramatic changes, closer to when the first galaxies were just starting to form.”
Light travels at a speed of 186,000 miles a second, or about 6 trillion miles (10 trillion km) a year. Astronomers can use light-speed as a kind of time machine, and seeing light emitted from objects very far away shows them as they were in the past.
In this case, the galaxy’s light started traveling 13.2 billion years ago, right after the Big Bang that created the universe.
The distance is measured using what is called red shift, a kind of Doppler effect of light. Just as a train’s whistle seems to change in pitch as the train approaches and passes, light’s color also shifts.
This galaxy has a red shift of 10, making it the farthest and oldest ever seen. The previous record, set in October, was a galaxy with a red shift of 8.5.
Just 200 million years later, stars began forming at a much faster rate, the researchers said.
“However, only when the James Webb Space Telescope is launched will these first phases of galaxy build-up between (red shifts of 15 and red shifts of 10) be revealed,” they wrote.
Hubble, launched in 1990, can see the faint light from these ancient galaxies because it orbits outside the Earth’s atmosphere. The more powerful Webb telescope is scheduled for launch in 2015.
(Reporting by Maggie Fox)
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