An article published on the arXiv server reports the observation of gravitational waves emitted by the merger of two black holes with very different masses. The scientists from the LIGO and Virgo collaborations used the data collected by their detectors to examine this merger, the first in which the mass of the two objects is so asymmetric given that the estimates made indicate that they were 8 and 30 times the Sun’s. The event, cataloged as GW190412, produced waves with shapes different from those found so far in mergers between objects of similar masses and contain information that allowed to obtain more precise measurements of the pair’s physical properties. It also made it possible to conduct new tests of the theory of general relativity, confirmed once again.