Supervoid: Scientists just discovered an unexplained hole in the universe
It's the largest-known phenomenon that's ever been discovered.
But it's just empty space.
This supervoid is 1.8 billion light years across (the distance light can travel in a year).
It would normally be expected to contain around 10,000 galaxies.
It was picked up a Nasa telescope in Hawaii and scientists can't explain why it's empty.
But it could shed some light on a spot in the universe that's much colder and has been a mystery for over a decade.
Istvan Szapudi from the University of Hawaii is the leader of the team which discovered the supervoid.
He's been looking for it for eight years and says it's in an area of the universe that hasn't been surveyed much.
It's claimed the area is too big to fit into how we think about space at the moment - that it is "too big to exist."
The supervoid sits in a region of space which is much colder than other parts of the universe, and although it is not a vacuum or a totally empty space, it seems to have around 20 per cent less matter than other regions.
The study suggests the supervoid may be draining energy from light travelling through, which is why the area around it is so cold.
Because getting through such a big hole takes hundreds of millions of years, even at the speed of light, and photons (what light is made of) slow down as they cross the universe, the void, is continually expanding and getting colder.
However the scientists claim that the void can only account for around 10 per cent the temperature drop in the cold spot. So what is going on? The supervoid is a bit of a mystery.
The supervoid is about three billion light-years away from Earth. That's been described as a relatively short distance in the cosmic scheme of things.
The researchers have published their findings in the journal Monthly Notices of the Royal Astronomical Society.