The International Space Station is orbiting the Earth at an altitude of 400 Km, give or take.  This gives it an orbital period of about 90 minutes.  Keen observers on Earth can track these movements and look for the ISS in the sky as it passes overhead.  Some of the keenest observers even take photos, and plan for incredible transits.  In the case below, we can see the ISS transit the Sun, twice in one day. A carefully chosen time and place on Earth by the photographer Hartwig Luethen, this photo was taken on August 22nd, during two successive transits....