Astronauts on the ISS Watch 16 Sunrises Every Single Day
Answers: “how fast does the iss travel?”
The International Space Station moves at roughly 28,000 kilometers per hour — about 7.66 km every second. At that speed you could go from Mumbai to Delhi in under three minutes.
The consequence: the ISS completes one full lap of Earth every 90 minutes or so, which means astronauts aboard experience 16 sunrises and 16 sunsets every 24 hours.
Every 45 minutes, day flips to night or night to day. The visual is reportedly never boring — a thin blazing arc of atmosphere igniting along Earth’s edge, colors no camera fully captures — but living with it is another matter:
- Astronauts’ body clocks would be destroyed by the light cycle, so the station runs on GMT and crews sleep by schedule, not by sun, with sleeping quarters sealed against the every-45-minutes dawn
- The station’s solar panels swivel constantly to track a sun that “rises” 16 times daily
- The orbital speed also means astronauts age very slightly slower than people on Earth — a few milliseconds per six-month mission, thanks to relativistic time dilation
Why so fast, though? It’s not for convenience — it’s the only way to stay up. Orbit is a controlled fall: the ISS is perpetually falling toward Earth, but moving sideways so fast that the planet’s surface curves away beneath it at exactly the rate it falls. That’s all an orbit is — missing the ground forever, as Douglas Adams almost put it.
And you can watch it happen. The ISS is the third-brightest object in the sky after the Sun and Moon; NASA’s “Spot the Station” service tells you when it passes over your city. That bright dot gliding silently across your evening sky is seven people falling around the world at 28,000 km/h — probably watching their fourth sunset since lunch.