The International Space Station orbits about 250 miles above Earth, traveling at roughly 17,500 miles per hour. At that speed, it completes a full lap around the planet every 90 minutes - about 16 orbits every 24 hours.
For astronauts on board, that means seeing the Sun rise and set 16 times in every Earth day. Sunrise, sunset, sunrise, sunset, every hour and a half. Their bodies can’t keep up with that, so they live on a strict 24-hour schedule synced to the time zone of Mission Control in Houston. Crew members use eye masks, lights, and routines to simulate proper night and day, otherwise their sleep would fall apart.
You can sometimes see the ISS yourself with the naked eye, especially around sunrise or sunset, when sunlight catches its solar panels. It looks like a fast-moving bright star crossing the sky in 3-4 minutes. NASA has free websites that tell you when it’ll pass over your house.
