The conspiracy emerged to explain how the density of matter in different galaxies appeared to be decreasing at the same rate from their centre to the outer edges – something that remained a mystery for close on a quarter of a century.

It continued to allude astronomers because galaxies are diverse, with many different ages, shapes, sizes, and numbers of stars. So why would they all have the same density structure?

The research team observed 22 middle-aged galaxies – peering back some four billion years in the past due to their great distance from Earth – in extraordinary detail, using the European Southern Observatory’s Very Large Telescope in Chile. It enabled them to create more complex models that better captured the diversity of galaxies in the universe.

Dr Caro Derkenne, the first author of the paper and an ASTRO 3D researcher from Macquarie University along with her colleagues found that the similarity in density might not be due to the galaxies themselves but in how astronomers were measuring and modelling them.