These images, taken by the ESA/NASA Solar Orbiter’s Polarimetric and Helioseismic Imager (PHI) instrument cover thirty minutes of the transit of Mercury’s silhouette across the Sun’s disc. PHI observed the transit for more than three hours. Mercury is seen as a black circle in the lower right quadrant of the image. It is distinctly different from the sunspots that can be seen higher up the Sun’s disc.