The universe has ten times more galaxies than scientists thought

The census of galaxies just got a whole lot bigger. The observable universe is filled with ten times more galaxies than scientists previously thought there were, astronomers reported on Thursday.

Researchers used the Hubble Space Telescope and other instruments to come to the conclusion that there could be at least one or two trillion galaxies in the observable universe— ten times the 100 or 200 billion that was the previous estimate.


"It boggles the mind that over 90 percent of the galaxies in the universe have yet to be studied,” Christopher Conselice, the lead author on a new study on the topic and an astrophysics professor at the University of Nottingham, said in a statement. “Who knows what interesting properties we will find when we discover these galaxies with future generations of telescopes?”

When astronomers use telescopes to peer at distant stars, they are actually looking back in time, since the light takes a while to get to Earth. It’s a phenomenon that Ray Villard, of the Space Telescope Science Institute, compares to “a postcard that got lost in the mail.”

And over billions of years, small galaxies merged to create bigger ones, Villard told, like “big fish [eating] little fish.”

Ninety percent of galaxies in the observable universe are too dim and distant to be seen today, according to the new research; ten percent can be seen. With a more powerful telescope, the ancient smaller galaxies (which have since merged) could hypothetically become visible.

"These results are powerful evidence that a significant galaxy evolution has taken place throughout the universe's history, which dramatically reduced the number of galaxies through mergers between them — thus reducing their total number,” Conselice said in the statement.

The study was published in the the Astrophysical Journal.

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