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Astronomers Just Saw Farther Back In Time Than They Ever Have Before

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Hubble has proven once again, even after almost 26 years in space, just how special it is.

To look through the lens of a telescope is to peer back in time.

The light we view through it has spent hundreds, millions, even billions of years crossing the vastness of space to reach us, carrying with it images of things that happened long ago.

On Thursday, astronomers at the Hubble Space Telescope announced that they’d seen back farther than they ever have before, to a galaxy 13.4 billion light years away in a time when the universe was just past its infancy.

The finding shattered what’s known as the “cosmic distance record,” illuminating a point in time that scientists once thought could never be seen with current technology.

“We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble,” Yale University astrophysicist Pascal Oesch, the lead author of the study, said in a statement.

The galaxy, unpoetically named GN-z11, appears as an unremarkable, fuzzy, dark red splotch when it’s magnified from an image taken by the Hubble Telescope. But by measuring a phenomenon known as redshift, Oesch and his colleagues were able to look back in time to when the galaxy was brilliantly blue and incredibly hot, bursting with brand new stars that formed at a frenetic rate.

“It really is star bursting,” study co-author Gabriel Brammer, an astronomer at the Space Telescope Science Institute, told the Associated Press.


Redshift explains GN-z11’s dull crimson coloring: Because the universe is expanding, every object we see through a telescope is actually moving away from us. And as they move, the waves of light they emit stretch out, shifting in color from blue, which has a relatively short wavelength, down to red, whose waves are long. The phenomenon isn’t so different from the way the sound of a train deepens as it chugs away from the listener.

By measuring the degree of redshift, scientists can figure out how long light has been traveling to us through space, and thereby how long ago the thing that they’re looking at existed. Previously, the highest redshift number assigned to a galaxy was 8.68 — meaning it existed some 13.2 billion years in the past.

This means that the galaxy was around just 400 million years after the Big Bang — no time at all, in cosmic terms — to a period that is 97 percent of the way to the universe’s very beginnings.

(A note on time and distance: Light years are a measure of distance — how far light can travel in a year. But cases like this, they are an indicator of age. Since the light from GN-z11 has traveled 13.4 billion years to reach us, that means it’s been traveling for 13.4 billion years, so its source must be 13.4 billion years old.)
The universe was still a toddler at that stage — hazy, cold and shrouded in a fog of hydrogen gas.


But the stars in GN-z11 and other galaxies like it were fast-growing giants that would have swiftly heated things up, “frying” the gas around them, the scientists told the BBC. And new ones were popping out all the time; GN-z11 formed stars at a rate 20 times faster than our own Milky Way.

For a brief time, they burned brilliantly. And then they burned out.

The researchers say that the existence of such a hot and active galaxy shows how little they know about the universe’s toddler years. Marijn Franx, a co-author from the University of Leiden, noted in the statement that previous research suggested that such a thing wasn’t possible.

How exactly the brilliant GN-z11 was created “remains somewhat of a mystery for now,” added his colleague Ivo Labbe.

There is some skepticism about GN-z11’s age from other scientists. Speaking to the AP, Richard Ellis, an astronomer at the European Southern Observatory who found the previous record-holder for farthest galaxy ever seen, noted that the astronomers studied a spectrum of light that’s seen as less reliable.

Ellis wrote in an email that those light signatures are “noisier and harder to interpret,” and that for GN-z11 to be visible it would have to be three times brighter than typical galaxies.

Oesch responded that his team made sure “this was as clean as possible a measurement,” and noted that the technique he used is now becoming standard.
This will probably stand as one of Hubble’s last big accomplishments and almost certainly its most distant find. The decades-old behemoth hasn’t been repaired since 2009, and will likely be retired after NASA launches its new space telescope, the James Webb, in 2018.

Exactly how that happens is still up in the air, so to speak. The telescope could be booted into a higher “parking orbit,” where it will float for centuries as yet another piece of space junk. Or it might be summoned back to Earth via a robotic craft, which would guide it on a fiery descent into the Pacific Ocean.

But both options are still years away. If anything, Oesch said, the new find shows that after more than two decades aloft, Hubble has still got it.

“Hubble has proven once again, even after almost 26 years in space, just how special it is,” he told the BBC. “When the telescope was launched we were investigating galaxies a little over half-way back in cosmic history. Now, we’re going 97 percent of the way back. It really is a tremendous achievement.”


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“Astronomers Just Saw Farther Back In Time Than They Ever Have Before”