Astronomers have discovered a curious empty section of space which is missing about 10,000 galaxies. The "supervoid", which is 1.8billion light years across, is the largest known structure ever discovered in the universe but scientists are baffled about what it is and why it is so barren.It sits in a region of space that is far colder than other parts of the universe and, although it is not a vacuum, it seems to have around 20% less matter than other regions.Although the Big Bang theory allows for areas that are cooler and hotter, the size of the void does not fit with predicted models. Simply put, it is too big to exist. A supervoid is an empty section of space defined by the lack of superclusters.István Szapudi, of the University of Hawaii at Manoa, described the object as possibly "the largest individual structure ever identified by humanity".It was picked up using Hawaii's Pan-STARRS1 telescope located on Haleakala, Maui, and Nasa's Wide Field Survey Explorer satellite.Scientists are unclear about what this desolate space is.But this is not the first mystery of outer space that has left experts scratching their heads.The latest study suggests that the "supervoid" could be draining energy from light travelling through, which is why the area around it is so cold.Getting through such a big hole takes hundreds of millions of years, even at the speed of light, and photons of light slow down as they cross because the universe - and therefore the void - is continually expanding.But the scientists claim that the void can only account for about 10% of the temperature drop in the cold spot."It just pushed the explanation one layer deeper," said Dr Roberto Trotta, a cosmologist at Imperial College, London.The supervoid is only about 3billion light years away from Earth, a relatively short distance in the cosmic scheme of things."Supervoids are not entirely empty, they're under-dense," said András Kovács, a co-author at the Eötvös Loránd University in Budapest."This is the greatest supervoid ever discovered."Given the combination of size and emptiness, our supervoid is still a very rare event."We can only expect a few supervoids this big in the observable universe."The researchers have published their findings in the journal Monthly Notices of the Royal Astronomical Society...