When Mercury Transits the Sunlight, you can see it as being a small black dot silhouetted towards the Sunlight's disk. Right after a single orbit, Mercury has rotated one.5 instances, so after two finish orbits exactly the same hemisphere is again illuminated. For a few years it had been imagined https://apps.apple.com/de/app/merkur-spieleraum-online/id6477957809