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Scientists say 1 in 5 galaxies are hidden by cosmic dust, sparking alien hopes
November 24, 2021
Astronomers now believe that one in five galaxies are hidden from us behind cosmic dust, meaning that there are far more observable galaxies than initially thought.
This also means that we have no idea what – or who – lurks beyond the dust, until now.
The groundbreaking revelation comes after two previously invisible galaxies heavily obscured by dust, called REBELS-12-2 and REBELS-29-2, were discovered by radio telescopes in Chile's Atacama Desert.
Both had been hidden from NASA's Hubble Space Telescope by the dust.
Those who made the discovery now estimate that 20% of the universe's galaxies are hidden in a similar way.
Researchers at the University of Copenhagen's Niels Bohr Institute, which conducted the recent study published in the journal Nature, hope that new technologies such as the upcoming James Webb Space Telescope will help us find more of these hidden galaxies.
Pascal Oesch, associate professor of the Niels Bohr Institute, said: "We were looking at a sample of very distant galaxies, which we already knew existed from the Hubble Space Telescope.
"Then we noticed that two of them had a neighbour that we didn't expect to be there at all.
"As both of these neighbouring galaxies are surrounded by dust, some of their light is blocked, making them invisible to Hubble."
REBELS-12-2 and REBELS-29-2 were spotted by the Atacama Large Milimeter Array (ALMA) ground-based radio telescopes.
The ALMA, which started observations in 2011, has five times better spatial resolution than the Hubble which launched in 1990.
Consequently, there are hopes that more advanced technologies will allow us to observe past the cosmic dust.
The latest in space telescope technology is the James Webb Space Telescope, expected to launch on December 22 after 25 long years of development.
Its central aim is to help us better understand how galaxies are formed, but its increased sensitivities will also allow us to shed light on hidden galaxies.
Oesch continued: "The next step is to identify the galaxies we overlooked, because there are far more than we thought.
"That’s where the James Webb Telescope will be a huge step forward.
"It will be much more sensitive than Hubble and able to investigate longer wavelengths, which ought to allow us to see these hidden galaxies with ease."
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