Astrophysicists detect first black hole-neutron star mergers

A long time ago, in two galaxies about 900 million light-years away, two black holes each gobbled up their neutron star companions, triggering gravitational waves that finally hit Earth in January 2020. Astrophysicists' observation of the two events — detected just 10 days apart — mark the first-ever detection of a black hole merging with a neutron star.