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There Are Ten Times as Many Galaxies as Previously Thought

By these latest estimates, two trillion galaxies are scattered throughout the vast universe

Hubble's eXtreme Deep Field Image (NASA)
smithsonian.com

The number of galaxies scattered throughout the universe is beyond imagination. But that already massive number just got even larger. A new analysis of images from the Hubble Space Telescope suggest that there are roughly two trillion galaxies populating space—ten times previous estimates, reports the Agence France Presse.

This latest analysis uses mathematical models to estimate the number of both visible and hidden galaxies in snapshots like Hubble's famous Deep Field image. Using this method, Christopher Conselice, who studies galaxy formation at the University of Nottingham, and his team came up with a surprising conclusion: The models suggest that only about ten percent of galaxies in the universe are observable from Earth. That means our current technology misses about 90 percent of what’s out there, including trillions of galaxies, each with tens or hundreds of billions of stars. The study can be found on the preprint server arXiv.org and will be published in Astronomical Journal.

“It boggles the mind that over 90 percent of the galaxies in the universe have yet to be studied,” Conselice says in a press release. “Who knows what interesting properties we will find when we observe these galaxies with the next generation of telescopes?”

Phil Plait at Slate explains that this finding does not mean that the universe is ten times bigger than we thought or that there are tens times the amount of stars. It means those stars are divvied up into many more galaxies than we previously believed. “It’s like knowing there are a million people in a city, and finding out they live in 100,000 buildings when you thought they were only in 10,000,” writes Plait. “There are more buildings, but not more people.”

The research also reveals something about the history of the universe. About 13 billion light years away, when scientists believe the universe began, researchers found that the galaxies are both smaller and roughly ten times more dense than just a few billion years later. This means that over time, galaxies merged with one another creating larger and more complex systems, confirmation of something known as the top-down formation of the universe.

The study also throws out another mind-blowing thought: every single speck of sky visible from Earth contains a galaxy, writes Plait. So take a look at the night sky tonight and know that although you can't see them, no matter where you look, the sky is packed with galaxies.

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About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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