ISS facts
How fast does the ISS travel?
The International Space Station orbits Earth at about 28,000 kilometers per hour — roughly 17,500 mph, or 7.66 kilometers every second. At that speed it completes a full lap of the planet every 90 to 93 minutes, giving its crew around 16 sunrises and sunsets a day.
Why the ISS has to move that fast
Orbiting is controlled falling. The station is constantly pulled toward Earth by gravity, but it moves sideways so quickly that the planet's surface curves away beneath it at the same rate it falls. At the ISS's altitude of about 400 km, the math works out to almost exactly 7.66 km/s — any slower and it would spiral down, any faster and it would climb to a higher orbit. The speed isn't a design choice; it's what physics demands at that height.
How fast is that, really?
| Object | Speed |
|---|---|
| ISS | ~28,000 km/h |
| Rifle bullet | ~4,300 km/h |
| Concorde (retired) | ~2,180 km/h |
| Commercial jet | ~900 km/h |
| Formula 1 car | ~350 km/h |
Put differently: the station crosses the continental United States in about ten minutes, and could fly from London to New York in around twelve.
What its speed means for spotting it
Because the ISS moves so fast, a visible pass is short — typically two to five minutes from horizon to horizon. It crosses the sky noticeably faster than any aircraft, with a smooth, steady glide and no blinking lights. That speed is exactly why alerts help: check whether it's visible tonight or get a free email before each pass so you're outside at the right moment.
Does the ISS ever slow down?
Constantly, by a tiny amount. Even 400 km up there are wisps of atmosphere, and the drag lowers the station's orbit by about two kilometers a month. Visiting spacecraft periodically fire their engines to boost it back up — you can sometimes see these reboosts as small jumps in the altitude reading on the live tracker, which shows the station's current speed and altitude computed from the latest orbital data.