“Mergers of black holes with neutron stars are exceptionally rare in the Universe.  “An actual merger of a neutron star with a black hole happens, perhaps, once every million years in a galaxy.  To see one in the Milky Way, we would have to watch for a very long time,” Harald Pfeiffer, group leader in the Astrophysical and Cosmological Relativity department at Max Planck Institute for Gravitational Physics (AEI) in Potsdam, Germany, told The Daily Galaxy about recent neutron star-black hole merger of GW200105, detected by LIGO and Virgo in the past five years that have opened a completely new new way of observing the Universe.