A large international team of astronomers has used NASA’s Hubble Space Telescope to learn more about so-called quenched galaxies – galaxies that are no longer forming stars. This image shows 20 of the quenched galaxies (NASA / ESA / M. Carollo, ETH Zurich). Quenched galaxies in the distant past appear to be much smaller than the quenched galaxies in our modern-day Universe. This has always puzzled astronomers — how can these galaxies...