(CN) - The previous estimate of 200 billion galaxies has turned out to be a conservative estimate: scientists now believe there are actually 10 times that figure - at least 2 trillion of them.
Using data recorded by the Hubble Space Telescope, researchers found that while there are at least 2 trillion galaxies in the observable universe, there are likely many more that can't be detected by modern technology, NASA said Thursday.
"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," lead researcher Christopher Conselice said.
The previous estimate of galaxies within the observable universe was established in the 1990s from Hubble Deep Field images.
The new estimate was made using deep space images from the Hubble Space Telescope, data from the team's previous work, and other published data. Conselice and his team converted the images into 3-D in order to establish more accurate measurements of the number of galaxies at different times in the universe's history, while also using mathematical models to infer the existence of galaxies that can't be observed by current telescopes.
Based on the team's findings, roughly 90 percent of the galaxies in the observable universe are too faint and too distant to be seen — yet.
By analyzing the data, the team looked more than 13 billion years into the past, which showed that galaxy creation varied over the universe's history. The findings suggest that an evolution has taken place that merged galaxies together, significantly reducing their total number.
"This gives us a verification of the so-called top-down formation of structure in the universe," Conselice said.
The decreasing volume of galaxies also contributes to the solution of Olbers' paradox - that the darkness of the night sky contradicts the theory of an eternal and infinite universe that neither expands nor contracts.
The team found that there are so many galaxies that, in theory, every point in the sky contains part of a galaxy. Most of these galaxies are invisible to the human eye and modern telescopes due to various factors - including the universe's dynamic nature and the absorption of light by intergalactic dust and gas - that ensure the night sky remains mostly dark.
Image: NASA, ESA and the HST Frontier Fields team (STScI), Acknowledgement: Judy Schmidt
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