Look up. There are 10 times more galaxies than once thought

You think your attic’s full of stuff – try the universe. By remapping the deepest corners of the universe, scientists at Nottingham University in the U.K. now believe there are 10 times as many galaxies in the universe than previously thought. Their findings, reported this week in The Astrophysical Journal, recycle data collected over 20 years by one of the oldest man-made sentinels in space — the Hubble telescope — to offer new perspective on the observable universe.

“It boggles the mind that over 90 percent of the galaxies in the universe have yet to be studied. Who knows what interesting properties we will find when we observe these galaxies with the next generation of telescopes,” Christopher Conselice, an astrophysicist who led the study, said in a statement.

His team reached this conclusion by reanalyzing the Hubble Deep Field surveys, a set of images captured in the mid-1990s and early 2000s. The concept behind the surveys was akin to taking a photo with a long exposure. Pointing Hubble at one section of the sky for a long period of time allowed the telescope to capture extremely faint details of the cosmos. The faintest points represent the earliest corners of the universe. The first Hubble Deep Field, for instance, lasted 100 hours over the Christmas season in 1995, each second crawling deeper and deeper into history.

Conselice’s team took this data and similar batches from telescopes across the world to peer 13.7 billion years into the past. Despite covering huge swaths of the sky, the images from each telescope represent a small sliver — a pencil beam — of the total universe. Conselice and his colleagues carefully teased apart these pencil beams, in order to create 3-D maps of the universe.

This animation starts with a lookback into the early Universe. The local, modern Universe with large and evolved galaxies can be seen to the left. The distant, early Universe with many tiny and primordial galaxies can be seen to the right. These galaxies grew through mergers to the galaxies we see today. The animation slowly turns by 90 degree and ends with a view similar to the Hubble Deep fields. Photo by ESA/Hubble, M. Kornmesser

The team found galaxies aren’t uniformly distributed across the evolution of space. The early universe contained about 10 times more per unit volume compared to today, their study reports. Overall, they estimate 2 trillion galaxies populate the universe, but also suspect 90 percent are too faint for detection even with the best of today’s telescopes.

“Who knows what interesting properties we will find when we study these galaxies with the next generation of telescopes,” Conselice said.