The Giant Arc is a claimed large-scale structure discovered in June 2021 that spans 3.3 billion light years. This structure of galaxies exceeds the 1.2 billion light year size threshold of the currently accepted model of cosmology, potentially challenging the cosmological principle that at large enough scales the universe is considered to be the same everywhere (homogeneous) and in every direction (isotropic). The Giant Arc consists of galaxies and galactic clusters, as well as gas and dust. It is located 9.2 billion light-years away at redshift ~0.8, and it stretches across roughly 1/15th of the radius of the observable universe. It was discovered using data from the Sloan Digital Sky Survey by the team of Alexia M. Lopez, then a doctoral candidate, now a post-doctoral researcher in cosmology at the University of Central Lancashire.