Just how large is the universe? Far larger than initially thought. Astronomers have discovered that there are at least 10 times as many galaxies in the universe.
Using data from the NASA/ESA Hubble Space Telescopes, astronomers have been able to perform an accurate census of the number of galaxies in the universe. In the mid-1990s, it was estimated that the observable universe contained between 100 to 200 billion galaxies. However, the latest data and images gathered have revised that number upwards significantly to the tune of over two trillion galaxies.
The team of researchers used deep-space images from the Hubble and a number of sources of data to make accurate measurements of the number of galaxies that existed at different times in the universe’s history. They determined that approximately 90% of galaxies are too faint and far away to be seen.
“It boggles the mind that over 90% of the galaxies in the Universe have yet to be studied,” lead researcher Christopher Conselice of the University of Nottingham, UK, said in a statement. “Who knows what interesting properties we will find when we observe these galaxies with the next generation of telescopes.”
In order to observe the galaxies, the team of researchers had to compile data going back 13 billion years ago because they were studying parts of the universe that were up to 13 billion light-years away. This allowed them to observe the evolution of the universe and conclude that the early universe contained more galaxies than it does today. Some of the small dwarf galaxies merged together to form larger galaxies as time went by.
“This gives us a verification of the so-called top-down formation of structure in the Universe,” Conselice said.
The confirmation that the number of galaxies has been decreasing as time has progressed also helps to explain why the night sky is so dark. There was a theory that the night sky should be permanently light given that the universe is filled with an infinite number of stars. However, this theory was created before the understanding of the universe’s dynamic nature.
“This is very surprising as we know that, over the 13.7 billion years of cosmic evolution since the Big Bang, galaxies have been growing through star formation and mergers with other galaxies,” Conselice said in a separate statement. “Finding more galaxies in the past implies that significant evolution must have occurred to reduce their number through the extensive merging of systems.”
Just think, there could have been a planet with intelligent life on it similar to ours in a galaxy 13 billion light-years away (that’s 13 billion years ago) and we will never know!