How do you pinpoint titanic collisions that occur millions or billions of light-years away? First, by surveying large areas of the sky. Second, by teaming up with observatories around the world. Scientists have been searching for kilonovae, when two neutron stars or a neutron star and a black hole collide and set off brief, but fantastic light shows as they merge. Such a collision can cause an enormous eruption that sends out bright cascades of light and ripples in space-time.