Astronomers using the James Webb Space Telescope (JWST) have made an exciting discovery: the dusty material in a galaxy five billion light-years away looks remarkably similar to the dust found much closer to home.
This finding is helping scientists better understand how stars, black holes, and even planets may have formed in the early universe.
The discovery was made by a team of researchers led by Anna Sajina, a professor of astronomy at Tufts University.
She studies how galaxies and black holes formed, especially in the earlier days of the universe. But there’s a big challenge: much of this activity is hidden by dust, which blocks the light astronomers need to observe.
This dust, made up of tiny grains of carbon, silicon, iron, and other elements, absorbs light from stars and re-emits it in the infrared—light we can’t see with our eyes.
To study galaxies from billions of years ago, scientists have had to make educated guesses about the dust in those galaxies, assuming it’s similar to the dust in our own Milky Way.
Until now, there wasn’t a good way to test that assumption.
But thanks to the powerful infrared capabilities of JWST, astronomers can finally take a much closer look.
Sajina’s team studied a distant galaxy named SSTXFLS J172458.3+591545. The light from this galaxy took about five billion years to reach us, so we’re seeing it as it looked five billion years ago.
The galaxy contains a growing black hole hidden deep within thick clouds of dust and gas—what astronomers call an active galactic nucleus.
With JWST’s advanced sensors, the team detected frozen molecules—ices of water, carbon monoxide, and carbon dioxide—coating the dust grains in this galaxy.
This is the first time all of these frozen molecules have been detected together in solid form outside the nearby universe. While scientists have long detected similar molecules in gas form, directly observing them as ices on dust grains is much more difficult, especially in faraway galaxies.
What’s fascinating is that the chemical makeup of this icy dust is nearly identical to what we see in our own galaxy. That means galaxies forming planets five billion years ago had the same basic building blocks we do.
In other words, the raw materials for making planets like Earth were already present far back in time and far across space.
This discovery also tells scientists more about how dust was arranged in such galaxies. The presence of ice suggests that the dust is packed into a dense central region, which matches other findings about this galaxy.
By confirming that this distant dust resembles the dust in our cosmic neighborhood, astronomers can now make more accurate predictions about how stars and planets formed in the early universe.
