A "spherical blob" approximately 1.8 billion light years across has been identified as the largest single structure that humanity has ever seen.

Dubbed a "supervoid", the giant hole has been described as “the largest individual structure ever identified by humanity" by Dr. István Szapudi of the University of Hawaii at Manoa, one of the lead researchers on the project. 

According to The Guardian, the team were looking for a void or a hole as a result of the fact that about 10 years ago, they spotted an unusually cool spot in that area. As it turns out, the supervoid was blocking the light of around 10,000 galaxies that should have been in that area.

The so-called "cold spot" is circled in the bottom right of this image (Pic via ESA)

It is not, in fact, an entirely empty space, but rather "under-dense", and while that doesn't sound all that interesting, it seems that this is still a very unusual. Dr. András Kovács of Eötvös Loránd University in Budapest stated that "in 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".

However, scientists are still stumped by the cold spot, and stated that the new question is how did the giant supervoid form, and does this fit with existing theories on the development of the universe after the Big Bang. 

Via The Guardian