Last updated: 11 July 2026
Closer than most people expect
Compared to the vast distances involved in planetary astronomy, the ISS is remarkably close — close enough that the distance from a city to a neighbouring one on Earth's surface can exceed the ISS's altitude. Its orbit sits in a region called low Earth orbit (LEO), well below the Van Allen radiation belts and low enough that atmospheric drag is still noticeable, requiring periodic reboosts to keep it from gradually losing altitude.
Why the altitude isn't perfectly fixed
The ISS's orbit isn't a static number — it drifts downward over time due to residual atmospheric drag at that altitude, and mission controllers periodically fire thrusters (often using a visiting cargo spacecraft) to boost it back up. Altitude is typically maintained somewhere in the 400–420 km range, though it has ranged as low as roughly 330 km and as high as about 460 km at different points in the station's history.
Fast enough to circle the planet in under an hour and a half
To stay in orbit at that altitude without falling back to Earth, the ISS has to travel extremely fast — about 7.66 kilometres per second, or roughly 27,600 kilometres per hour. At that speed, it completes a full orbit of the planet in about 93 minutes, meaning the crew on board experiences a sunrise or sunset approximately every 45 minutes, or around 16 of each per day.
How that compares to true "distance" in space terms
It's worth putting the ISS's altitude in context: at roughly 400 km, it is less than 0.03% of the distance from Earth to the Moon, and a vanishingly small fraction of the distance to any planet. In astronomical terms, the ISS is essentially still "at" Earth — everything discussed elsewhere on this site, from the Moon's monthly swing to Voyager 1's multi-decade journey, operates on a completely different scale.
| Object | Approx. distance from Earth |
|---|---|
| International Space Station | ~400–420 km |
| Moon (average) | ~384,400 km |
| Mars (closest approach) | ~56,000,000 km |