Universe contains 10 times more galaxies than our last guess

14 Oct 2016

Milky Way galaxy illustration. Image: Alex Mit/Shutterstock

As if space wasn’t mind-boggling enough, a team of astronomers using the Hubble Space Telescope has found that the population of galaxies in the universe is 2trn, 10 times more than we once thought.

The updated census of known galaxies in the universe was conducted by a team of astronomers from the University of Nottingham, and the results were significantly boosted thanks to the spotting of some lesser galaxies out there.

In its research published in the Astrophysical Journal, the team revealed that there are millions of ‘tiny’ galaxies out there, each with a weight of only around 1m suns.

Future Human

The researchers combined data from many of our ground and space-based telescopes and then calculated the number of galaxies that have been extinguished over time.

The resulting number showed that these small, hidden galaxies boosted the number of known galaxies to 2trn, 10 times more than previously thought.

However, this number is only an estimate as we can only see galaxies that have emitted light and that have reached Earth within the observable universe.

Even within this observable universe, our current level of astronomy only allows us to glimpse 10pc of this, leaving a lot of universe we are never likely to see.

Could answer a number of astronomical questions

“We are missing the vast majority of galaxies because they are very faint and far away. The number of galaxies in the universe is a fundamental number we would like to know, and it boggles the mind that over 90pc of the galaxies in the universe have yet to be studied,” said Prof Christopher Conselice.

“Who knows what interesting properties we will find when we study these galaxies with the next generation of telescopes. These galaxies will likely hold the clues to many outstanding astrophysical issues.”

Conselice and his team now predict that its new census will have considerable implications for astronomy in the future and could possibly answer one of the oldest but most fundamental questions of astronomy: why is the sky dark at night?

Because this census reveals that galaxies are likely forming by the merging of smaller ones together, this would decrease the number of systems over time – giving an answer to Oblers’ paradox.

“To find that there were in fact more galaxies in the past implies that that significant evolution in galaxies must have occurred to reduce the number of galaxies through extensive merging of systems,” Conselice said.

“This also gives us a verification of the top-down formation of structure in the universe.”

Colm Gorey was a senior journalist with Silicon Republic