A survey done with data collected over two decades by the Hubble telescope revealed that the universe is home to 2 trillion of galaxies, up to ten times longer than astronomers believed. The study, led by astrophysicist Christopher Conselice of the University of Nottingham, in England, took fifteen years to complete and will be published in the journal scientific Astrophysical Journal. >According to Conselice, 90% of these galaxies cannot be observed from the Earth, leaving only 10% to be picked up by the instruments. Part of the light emitted in the space by the distant objects has not yet arrived here on the planet.
"most of them have very weak signals or are too far away. Who knows what interesting properties do we find when we study these galaxies with the next generation of telescopes?" said Conselice, in a note.
The exact amount of galaxies intrigued scientists since the discovery of Edwin Hubble. The american astronomer, has detected that the called nebulae were galaxies outside of the Milky way, and that could make the number increase.
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Map of galaxies
The first step to find the number was to convert the images captured by the Hubble 2D to 3D. Then, the scientists have made calculations to find out the density of galaxies and the volume of the regions mapped to try and discover how many galaxies could be seen. The analysis covered 13 billion years, a time very close to the Big Bang – the moment in which science believes that the universe had origin – and came to the number 2 trillion. According to the scientists, in the beginning of the universe there were even more galaxies, about ten times more.
"This is very surprising, because we know that, over the 13.7 billion years of cosmic evolution since the Big Bang, galaxies were growing through of star formation and mergers with other galaxies. Find more galaxies in the past implies that the significant increase should have occurred to reduce the number of galaxies, with an extensive fusion systems," said Conselice.