James Webb Space Telescope (JWST) has given us a sneak peek into the universe’s distant past before. But in its latest image, it has revealed hundreds of ancient galaxies! The photo resembles Hubble’s famous Deep Field taken in 1995, and it shows new galaxies believed to be the earliest members of the universe.
[Related reading: This is how James Webb’s super-detailed photos compare to Hubble’s]
JWST Advanced Deep Extragalactic Survey (JADES)
It took a little over one month of Webb’s observing time for the JWST Advanced Deep Extragalactic Survey, aka JADES. But what’s that? JADES is a program that astronomers started to let Webb peer deeply into the universe and study some of the faintest and most distant galaxies.
This image is among the program’s first findings, and it includes many galaxies that existed during the universe’s early stages when it was under 600 million years old. It’s just a few hundred million years after the big bang, which is super-young in astronomy terms. But it gets better. As the JADES program continues, it will allow astronomers to search for the earliest galaxies that existed even earlier, when the universe was less than 400 million years old.
The photo’s significance
It’s amazing on its own that this photo is telling us, “Hey, these are some galaxies almost as old as the entire universe.” But as always, there’s more to it. The photo helps astronomers to identify galaxies that experienced multiple episodes of star formation. Studying these galaxies lets them travel back in time, so to say. They can look at how stars formed in the early years after the Big Bang and compare it with how they form now.
When light travels from far-off galaxies, it gets stretched out to longer wavelengths and redder colors. This is due to the universe expanding. This stretching is known as redshift. When measuring a galaxy’s redshift, astronomers can figure out how far away it is and when it existed in the universe’s early days.
This is a significant breakthrough for astronomers, considering that we only knew about a handful of these early galaxies so far. Before JWST, we could only observe a few dozen galaxies that had a redshift above 8. These galaxies existed when the universe was less than 650 million years old. But thanks to the (JADES), have now found almost a thousand of these very distant galaxies. So, we’re really starting to fill in the blanks about the early universe.
“Previously, the earliest galaxies we could see just looked like little smudges. And yet those smudges represent millions or even billions of stars at the beginning of the universe,” said Kevin Hainline of the University of Arizona. “Now, we can see that some of them are actually extended objects with visible structure. We can see groupings of stars being born only a few hundred million years after the beginning of time.”
How the first stars and galaxies form is one of the most fundamental questions in astronomy, and Webb’s new image could provide many of the long-awaited answers.