ISS Astronauts See 16 Sunrises Every Day

Astronauts on the International Space Station see 16 sunrises and 16 sunsets every 24 hours. The station travels at about 27,500 kilometers per hour (17,100 miles per hour) and circles Earth about every 90 minutes.

Divide 24 hours by 90 minutes and you get about 16 orbits a day. Each orbit passes through daylight and then through Earth’s shadow. On the station the Sun does not sink below a horizon. The station itself flies into the shadow, so day turns to night in minutes instead of hours. The crew keeps its clocks on Greenwich Mean Time, so the daily schedule does not follow the sunrises.