Telescopes are, in a way, time-travel machines to faraway galaxies. Light moves faster than anything in the Universe. For example, it takes light from the Sun 8 minutes to reach Earth, so the sunlight we feel on our faces is actually 8 minutes old. When astronomers use telescopes to look at galaxies in space, they find some that are close by and further away—that is, some younger and some very much older. Astronomers have even observed galaxies that are millions or billions of years old!

By studying the light from all kinds of galaxies, astronomers can glimpse the history of our Universe, and build up a ‘cosmic timeline’ of how galaxies form. Until recently, astronomers thought they had a pretty good idea of what this timeline should look like—but a new study has made them rethink some of the facts.

Two different teams of researchers were studying the most distant (and, therefore, the youngest) galaxy we know of, JADES-GS-z14-0. When the light we’re observing now left this galaxy—a whopping 13.4 billion years ago—the Solar System didn’t even exist yet! So, when the two teams of researchers analysed their data, they were surprised to find something unique that other young galaxies did not have.

What was it?... Oxygen.

That might not sound like a big deal: oxygen is everywhere around us! But there are certain things that galaxies can only have at specific ages - almost like a driver’s licence. 

Oxygen is produced in older massive stars and dispersed into the cosmos through supernova explosions when they die. For oxygen to be found in a galaxy as young as JADES-GS-z14-0, the stars we’re observing must be older than we thought they should be. The researchers essentially found a baby that had grown to the size of a teenager in a much shorter time than expected. 

Finding this rapidly growing galaxy gives astronomers more questions than answers about the first years of our Universe. Could galaxies have formed earlier in the cosmic timeline? Maybe they do not grow the way we think. How does this change what we know? That’s just the beauty of astronomy: finding more amazing questions where you could expect answers. Astronomers can only research further.

Image: The picture shows a very small section of the night sky with stars and galaxies. There is a pop-out zooming in on the galaxy JADES-GS-z14-0. The image in the pop-out is a diffused blue cloud with a bright white centre. Credits: ALMA (ESO/NAOJ/NRAO)/S. Carniani et al./S. Schouws et al/JWST: NASA, ESA, CSA, STScI, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Phill Cargile (CfA)