If you want to know what happened in the early years of the universe, you will need a very large and very specialized telescope. To the delight of astronomers and space buffs everywhere, the world has one: the James Webb Space Telescope.
In this episode of “The Conversation Weekly,” we talk with three experts about what astronomers have learned about the universe’s earliest galaxies and how just six months of data from James Webb is already changing astronomy.
The James Webb Space Telescope was successfully launched into space on December 25, 2021. After about six months of travel, setup and calibration, the telescope began collecting data and NASA released the first stunning images .
One of Webb’s nicknames is the “first light telescope.” That’s because Webb was specifically designed to be able to see as far back as possible into the early days of the universe and detect some of the earliest visible light.
You can see these galaxies in the images that NASA has released. Jonathan Trump, an astronomer at the University of Connecticut, is part of one of the teams working on some of the early data from James Webb. He was watching the release of the first live images and noticed a few things that many non-astronomers might have missed. “In the background, behind these beautiful arcs and spirals and massive elliptical galaxies, there are these little red spots. That’s what I was most interested in, because these are some of the earliest galaxies in the universe.”
Seeing any of these galaxies from the early days of the universe would be exciting, but right away, Jeyhan Kartaltepe, an astronomer at the Rochester Institute of Technology, found something exciting when he started digging into the data.
“One of the things we’ve learned is that there are more of these galaxies than we expected to see.” In addition to working to identify these early galaxies, Kartaltepe has been using Webb’s incredible resolution to study their structure and shape. “We expect there to be discs because discs form quite naturally in the universe whenever you have something spinning. But we’ve seen a lot of them, which has been a bit of a surprise.”
In addition to observing the shape of galaxies in the early universe, astronomers like Trump are beginning to be able to assess the chemical composition of these galaxies. It does this by looking at the spectrum of light that James Webb is collecting. “We look at these distant galaxies and look for particular patterns of emission lines. We often call this a chemical fingerprint because it’s really like a particular fingerprint of particular elements in a galaxy’s gas.”
The universe began with just hydrogen and helium, but as stars formed and elements fused, larger and heavier elements began to emerge and fill the periodic table as it is today. And like Kartaltepe, Trump is finding evidence that things were happening faster in the early universe than astronomers expected. “I would have guessed that the universe would have struggled to make the periodic table and build things. But that’s not what we found. Instead, the universe seems to have moved quite quickly.”
The discoveries coming out of James Webb are already changing the way astronomers think about the early universe and challenging much of the existing theory. But the really exciting part is that we’re only just beginning to see what this telescope is capable of, as Michael Brown, an astronomer at Monash University, explains.
“I’ve been in science papers that have used literally just a couple of minutes of data,” says Brown. “The image quality is so good that a couple of minutes can do amazing things.” But soon Webb will begin making follow-up surveys, taking deep-field images and looking at parts of the sky for days and even weeks. In the coming months, years and decades, Webb will continue to give astronomers plenty to work with, and astronomers like Brown are excited. “There’s all this complexity there, and we’re barely scratching the surface. These are going to be the things that people who are students now will devote their careers to. And it’s going to be wonderful.”
This episode was produced by Katie Flood and Daniel Merino, with sound design by Eloise Stevens. It was written by Katie Flood and Daniel Merino. Mend Mariwany is the executive producer of the show. Our theme music is by Neeta Sarl.
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