A 1.3bn light year-sized ring discovered by PhD student in Lancashire appears to defy the cosmological principle assumption

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.