When Brant Robertson saw a new measurement of the distance to a familiar galaxy, he laughed out loud.
For more than a decade, the galaxy had been a contender for the most distant ever observed. In 2012, Robertson and colleagues used data from the Hubble Space Telescope to show that the galaxy’s light had shone across the universe from about 13.3 billion years ago — less than 400 million years into the universe’s existence.
Not everyone believed it. “We got a lot of flak,” recalls Robertson, an astrophysicist at the University of California, Santa Cruz. “It seemed too implausible that it was at such a great distance.” It felt like he was going around claiming to have seen the Loch Ness monster.
But in September, the James Webb Space Telescope, JWST for short, aimed its massive mirror and sensitive spectrograph at the same galaxy and showed that Robertson and his colleagues were right. The galaxy’s light is indeed incredibly old, dating to just 390 million years after the Big Bang. It was like someone had drained the lake, and the monster was sitting there at the bottom.
And this galactic Nessie is not alone. So far, in its first year of observations, JWST has turned up thousands of distant galaxies dating to the early universe, many more than astronomers had expected. Some of those galaxies are brighter, more massive or more mature than astronomers would have thought. They are now scratching their heads trying to explain how the galaxies could have grown up so fast.
A lot of the extreme distances still need to be confirmed, but initial evidence suggests there’s reason to believe that many, if not most, of the galaxies really are that far away.
“I was expecting to find some galaxies at this [distance]. Some people were pessimistic; I wasn’t,” says Steven Finkelstein, an astrophysicist at the University of Texas at Austin. “But I was not this optimistic. I thought, ‘Yeah, yeah, we know what we’re going…
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