Pin It
The Pinwheel Galaxy
The Pinwheel GalaxyCourtesy of ESA/Hubble

Scientists spot an unprecedented number of Milky Way-like galaxies

After looking ten billion years into the past with JWST, researchers say that we must ‘rethink our understanding’ of the universe

The James Webb Space Telescope has beamed many exciting images back to Earth since blasting off in 2021, from pretty pictures of cartwheel galaxies and cosmic cliffs, to glimpses of potentially-habitable worlds that could harbour alien life. Now, it has helped uncover another scientific revelation, which could rewrite what we know about how the universe came into being.

In a new study by a team of international researchers, the JWST has been used to reveal galaxies similar to the Milky Way – ‘flat’ disc galaxies that rotate around a centre point, like CDs, and often contain vast spiral arms – in the early universe. This involved looking “back in time” ten billion years or more, to a turbulent period that occurred in the wake of the Big Bang, which is just what the pioneering telescope was made for.

The results were surprising, showing that many disc galaxies unexpectedly survived this period of frequent, violent galaxy mergers, which were expected to have destroyed their relatively fragile shapes. Comparing what they saw to past predictions, the team of scientists from the University of Manchester and Canada’s University of Victoria said that Milky Way-like galaxies were (or are – time in deep space gets a bit hazy) ten times more common than previously thought. This makes them the most common type in the known universe.

Why is this significant? Well, scientists believe that disc galaxies are particularly well-suited for life to develop – their relatively stable structures, for example, give them gravitational characteristics that are more favourable for planet formation. The fact that they existed in the early universe, in much greater quantities than previously thought, could mean many more opportunities for the development of alien life.

On the other hand, the discovery means we must “rethink our understanding” of how our own universe formed, says Christopher Conselice, professor of extragalactic astronomy at the University of Manchester, in a statement. “Using the Hubble Space Telescope [a JWST precursor] we thought that disc galaxies were almost non-existent until the universe was about six billion years old. These new JWST results push the time these Milky Way-like galaxies form to almost the beginning of the universe.”

In turn, this implies that most stars form and exist within galaxies like our own, challenging our current understanding of how galaxy formation works and how the landscape of the wider universe has evolved over time. 

The University of Victoria’s Leonardo Ferreira, the lead author of the study, has paid tribute to the JWST’s role in changing our understanding of galactic development, saying: “The fact that JWST finds so many [disc galaxies] is another sign of the power of this instrument, and that the structures of galaxies form earlier in the universe, much earlier in fact than anyone had anticipated.”