Three years ago the world witnessed the first direct detection of gravitational waves, from the merger of two black holes. It was the clearest evidence to date of the existence of gravitational waves and of black hole binaries.
Now, after years developing the necessary technology, the Event Horizon Telescope team announced the first clear imaging of a black hole, when illuminated by a luminous disk. The imaging is in the figure below, and refers to a black hole at the center of the M87 galaxy, with a mass of 6.5 billion solar masses.
Black holes rock! Pedro Cunha and Carlos Herdeiro have been leading tests of black holes and compact objects using ray-tracing analysis, and Vitor Cardoso just compiled a review on the status of dark and compact objects, and the observational bounds using both electromagnetic and gravitational waves.