Astronomy has entered a new era, one where light and gravity both play a role in understanding the Universe's craziest phenomena. On August 17, 2017, over 70 observatories around (and above) the world, including ones like LIGO and the Hubble Space Telescope, all spotted a flash of energy. This light came in many different flavours, and was consistent with a pair of dense neutron stars colliding in a cataclysmic "kilonova" explosion.