New baby pictures of the Universe taken by the James Webb Space Telescope show that galaxies started forming faster and earlier than expected.
The telescope was launched in December and is now orbiting the sun about a million miles away from Earth. Its giant mirror allows it to detect dim light that has traveled nearly the entire history of the 13.8 billion-year-old universe. That means it can effectively see what galaxies looked like long ago.
The snapshots captured so far have both thrilled and baffled scientists, as it turns out that many bright galaxies existed when the universe was very young.
“Just a few hundred million years after the Big Bang, there are already a lot of galaxies,” said Tommaso Treu, an astronomer at the University of California, Los Angeles. “JWST has opened a new frontier, helping us better understand how it all started.”
In research articles published in The Astrophysical Journal LettersTreu and other astronomers report the discovery of a galaxy dating back only 450 million years from its beginning, and another dating back 350 million years ago.
That latest discovery broke a Hubble Space Telescope record in 2016, when it managed to glimpse a galaxy called GN-z11, which existed about 400 million years after the Big Bang.
University of California Santa Cruz astronomer Garth Illingworth was part of the team that found GN-z11 and says it was “a huge surprise” to see it. But now, using their new space telescope, scientists know it wasn’t just a weird outlier — because they have at least two more examples.
“These galaxies we’re talking about are bright, so they hid just below the limits of what Hubble could do,” said Jane Rigby, an operations project scientist for the James Webb Space Telescope. “They were there waiting for us.”
Since astronomers started using JWST, some claim they’ve seen galaxies from even earlier times, such as 250 million years after the Big Bang. But those are more preliminary observations.
“We have a lot of faith in these two, but less in the other,” says Illingworth. “There’s definitely a lot of discussion going on.”
The two newly observed galaxies are both much smaller than our own galaxy, the Milky Way, and one appears unexpectedly elongated.
Because JWST has seen so many early, bright galaxies, astronomers have to rethink their old ideas about the evolution of the universe.
“It’s exciting to us, from a theoretical standpoint, that there may be some open questions about how these galaxies formed their stars so much earlier that we can detect large numbers of them,” said Jeyhan Kartaltepe of the Rochester Institute. of technology.
Finding such galaxies and building a better understanding of how the universe evolved into what it is today is why astronomers spent decades and $10 billion dollars designing and launching JWST.
“We can see that we are really on track to realize the dream of understanding galaxies in the earliest times,” says Illingworth. “The past few months have been exciting, but there is still a huge amount for us to learn.”