The Daily Double: ISS Transits the Sun Twice

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.

ISS transit x 2. Image Credit & Copyright: Hartwig Luethen

A carefully chosen time and place on Earth by the photographer Hartwig Luethen, this photo was taken on August 22nd, during two successive transits.  Since there is an hour and a half between the transits, the photographer has moved along with the Earth between the photos, and so the two transits are representative of two different distances from photographer to space station.  The upper transit, where the ISS appears larger, is from a distance of 656 km, while the lower second transit has the station 915 Km distant.  In either case the ISS is far closer than the Sun, at 150 Million Km.

Dedication to the art that is astrophotography.

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