Mars is about 62,000× wider than the International Space Station. Yet in this photo, taken by Tom Glenn in 2020, the ISS appears larger. Here’s why: - The ISS is 109 m across but only ~400 km above Earth, giving it an angular size of roughly 50 arcseconds. - Mars is 6,800 km wide, but was about 62 million km away, giving it an angular size of only ~22 arcseconds. So despite being vastly smaller, the nearby ISS looked larger in the sky. Capturing this photo was not easy: the transit was visible only along a strip of land about 90 meters wide, with the ISS silhouette sweeping across at an equivalent ground speed of 7.4 km/s. Tom Glenn had to be in exactly the right place, point his telescope in exactly the right direction, and nail the timing to a fraction of a millisecond. The final image was extracted from a video frame with an exposure of just 0.00035 seconds.