A blazar is an active black hole hurling jets of material directly at Earth. (Credit: NASA/Goddard Space Flight Center/CI Lab)

The Event Horizon Telescope made history on April 10 when it captured the first image of a supermassive black hole’s event horizon at the heart of galaxy M87. While there’s only one other target close enough to image that way – the black hole at the center of our own Milky Way – there are plenty of other targets where EHT’s sharp gaze can still make breakthroughs.