A supernova’s delayed reappearance could pin down how fast the universe expands
The catch: We have to wait until about 2037 for an answer
![a black background highlights several galaxies, with a half-circle orange arc](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2021/09/091021_kc_requiem_feat.jpg?fit=1030%2C580&ssl=1)
This cluster of galaxies, seen in a Hubble telescope image, contorts the light of a galaxy far behind it into arcs (orange).
A. Newman, M. Akhshik, K. Whitaker, Hubble/NASA, ESA