The supermassive black hole at the centre of M87. Left: The black hole feeds on a swirling disc of glowing plasma, driving a powerful relativistic jet across several thousands of light years. Bottom right: Approaching the black hole, gravity is so strong that light is severely bent, creating a bright (almost circular) ring. The north–south asymmetry in the emission ring is produced by relativistic beaming and Doppler boosting (matter in the bottom part of the image is moving toward the observer) and is mediated by the black hole spin (which is pointing away from Earth and rotating clockwise). Gravitational lensing magnifies the apparent size of the black hole’s event horizon into a larger dark shadow. The emission between the photon ring and the event horizon is due to emitting plasma either in the accretion flow and/or at the footprint of the jet (this emission is generally too dim to be detected by the EHT). Top right: While the EHT can zoom in very close to the event horizon, down to scales of only 0.01 light years (or 3.7 light days), i.e., a region comparable to the size of our Solar System, the relativistic jet (extended across several thousand light-years) can be probed using ALMA intra-baselines, recorded during the EHT observations (greyscale image).