The mysteries trapped in the corners of the universe are far more exciting than anyone could ever imagine. With each passing day and month, astronomers find new riddles and solve them in what is as puzzling as they are delightful. Sometimes astronomers find things in a place they least expect them to be. And that’s exactly what has happened with a group of astronomers looking for a simple sample of distant galaxies. Using radio waves, they discovered two “invisible” galaxies hiding behind a curtain of dust near the dawn of the universe. This curtain of dust was hitherto obscuring the galaxies from their view. The galaxies have been named REBELS-12-2 and REBELS-29-2 and they are among the most distant known galaxies.

Although the light from them has travelled 13 billion years to reach Earth, the galaxies are actually much farther away than that now — a staggering 29 billion light-years away. This is because the universe continuously expands. The astronomers used the Atacama Large Millimeter Array (ALMA), which captures radio waves.

The researchers have detailed their discovery in a paper published in the Nature journal. The study suggests that there were far more galaxies in the early universe than previously thought and raises new questions about our understanding of the universe. The astronomers have calculated that 10–20 percent of galaxies from the early universe may be hiding behind dust clouds, waiting to be discovered someday.

Astronomers usually use the Hubble Space Telescope to study cosmic mysteries. Though it has the most unobstructed view of the universe, Hubble can’t see everything as it watches the skies mostly in ultraviolet and visible wavelengths of light. So this group of astronomers used the ALMA telescope, which operates at wavelengths of 0.32mm to 3.6mm.

Pascal Oesch, an author of the study, said they were looking at a group of very distant galaxies with ALMA and then they noticed that two of them had a neighbour that wasn’t expected “to be there at all.” Both these neighbouring galaxies were surrounded with dust which blocked some of their light and Hubble couldn’t see them.

“We are trying to put the big puzzle about the universe’s formation together and answer the most basic question: ‘Where does it all come from?’” Oesch told New Atlas.

The astronomers are now waiting for more powerful instruments to be put in space so that their work can move forward. One of these power tools is the James Webb Space Telescope, which will specialse in infrared imaging of the cosmos. It is set to launch towards the end of this year, likely on December 22.