Have you ever wondered how a super-massive…nothing looks like? Astronomers might have an answer for you.

You are probably not very familiarized with the idea of nothingness, void or vacuum, notions which are often mind-boggling because of their lack of “physical” support in our day-to-day lives.

A vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than standard atmospheric pressure. A perfect vacuum with a gaseous pressure of absolute zero is a philosophical concept that is never observed in practice, not least because quantum theory predicts that no volume of space can be perfectly empty in this way.

However vacuum is a well-known (although not yet fully understood) constant in the outer space. Astronomers just caught a glimpse of the biggest vacuum ever to have been observed by human kind.

Situated between 6 and 10 billion light years away from us, the void is so vast that it spreads for more than 280 megaparsecs across, the equivalent of more than 1 billion light years. That gargantuan hole in our Universe is empty of any galaxies, stars, gas clouds and even dark matter, showing up as a blue tri-star on the map of the cosmic microwave background (radiation from the early Universe shining at weak radio wavelengths) observed in the direction of the Eridanus constellation.

"Although our surprising results need independent confirmation, the slightly colder temperature of the CMB in this region appears to be caused by a huge hole devoid of nearly all matter roughly 6-10 billion light-years from Earth," said Lawrence Rudnick of the University of Minnesota. Rudnick, along with Shea Brown and Liliya R. Williams, also of the University of Minnesota, reported their findings in a paper accepted for publication in the Astrophysical Journal.

As it usually happens in the scientific world, great discoveries come by accident. "One morning I was a little bored, and said, 'why don’t I look in the direction of the WMAP cold spot’," says Rudnick.

Astronomers are aware of the fact that, on large scales, the Universe is “filled” with voids. However, most of these voids are much smaller than the one found by Rudnick and his colleagues. In addition, the number of discovered voids decreases as the size increases.

"What we've found is not normal, based on either observational studies or on computer simulations of the large-scale evolution of the Universe," Williams said.

The absolute-cold portion of space is about 1,000 times larger than anything scientists would expect to appear between the galaxy clusters scattered in our ever expanding Universe.

It's hard even for astronomers to picture how big these things are," conceded Minnesota's Professor Lawrence Rudnick.

"If you were to travel at the speed of light, it would take you several years to get to the nearest stars in our own Milky Way galaxy; but if you were to go to this hole and enter one side, you'd have to travel for a billion years before you would get to the other side."

The astronomers have used data in their observations from the NRAO VLA Sky Survey (NVSS), a project that imaged the entire sky visible to the Very Large Array (VLA) radio telescope, part of the National Science Foundation's National Radio Astronomy Observatory (NRAO). Their careful study of the NVSS data showed a remarkable drop in the number of galaxies in a region of sky in the constellation Eridanus. The cold region in Eridanus was discovered in 2004.