Space

Astronomers have discovered a ring-shaped cosmic megastructure, the proportions of which challenge existing theories of the universe.

The so-called Big Ring has a diameter of about 1.3bn light years, making it among the largest structures ever observed. At more than 9bn light years from Earth, it is too faint to see directly, but its diameter on the night sky would be equivalent to 15 full moons.

The observations, presented on Thursday at the 243rd meeting of the American Astronomical Society in New Orleans, are significant because the size of the Big Ring appears to defy a fundamental assumption in cosmology called the cosmological principle. This states that above a certain spatial scale, the universe is homogeneous and looks identical in every direction.

“From current cosmological theories we didn’t think structures on this scale were possible,” said Alexia Lopez, a PhD student at the University of Central Lancashire, who led the analysis. “We could expect maybe one exceedingly large structure in all our observable universe.”