Hi, I’m Marley, the astronomer here at the Space Centre. This month we are taking a look at galaxies. These massive systems of stars, gas, and dust have been getting their moment in the spotlight thanks to the James Webb Space Telescope (JWST).

It seems like every few months, JWST has discovered a galaxy even younger, even further away, or even more massive. Or, you might see headlines about how this telescope has somehow broken cosmological theories that astrophysicists use to explain our universe. So, what is really happening?

Ideas surrounding galaxy formation and evolution go all the way back to the beginning of the universe: the Big Bang. Astronomers theorize that after the Big Bang, dark matter provided the scaffolding for baryonic (‘normal’) matter to latch onto. Over millions of years, denser areas of matter attracted each other through gravity. Eventually, what were once large clouds of gas and matter became primordial galaxies. The gravity of these young galaxies led to processes like collisions, disruptions, and mergers occurring over billions of years. These processes, and the stars forming in the galaxy, will impact the structure it will have at the end. Although, there are still a lot of questions marks in these ideas. The exact details surrounding how processes like mergers and collisions will influence an early galaxy, and when galaxies first began to form, are still fuzzy.

These primordial galaxies do not look anything like the grand spirals we think of when we imagine a galaxy. Primordial galaxies are small and clumpy, with no clear structure when compared to the galaxies we see today. Star formation would be occurring in tightly wound knots. Scientists saw these types of galaxies with the Hubble Space Telescope. Whereas, with an infrared telescope, JWST allows us to see galaxies from an earlier time in the universe than Hubble can.