How fast and how high the ISS flies
The Station orbits about 400-420 km above the ground at roughly 7.66 km/s - around 27,600 km/h. One lap of the planet takes about 93 minutes, so it goes round about 15.5 times a day and its crew see sixteen sunrises. The panel next to the globe shows the exact altitude and speed at this moment, worked out from the most recent orbital elements in the catalogue.
Its orbit is tilted 51.6° to the equator. That is why the dashed ground track snakes between 51.6° north and south, and why the Station can be seen from almost everywhere people live - though rarely from the far north or south.
How to see the ISS pass overhead
You can see the ISS without a telescope whenever two things are true at once: the Station is still in sunlight high above you, and your own sky is dark. That happens in the hour or two after sunset and before sunrise, and the tracker marks those passes as Visible.
- Look for a steady, bright white light moving smoothly across the sky - no blinking, no colours. It is often brighter than any star.
- It rises in the direction the pass card shows, climbs to its highest point and either sets or fades out as it enters Earth's shadow.
- The higher the peak elevation, the brighter and longer the pass. Anything above about 40° is worth going outside for.
Open a pass to see its path across your sky on a chart - the centre is straight overhead, the rim is the horizon - and add it to your calendar with a reminder ten minutes before. Our guide on how to see the ISS pass overhead goes into more detail.
Why the pass times can move
Pass predictions are only as good as the orbital elements behind them. The Station is low enough to feel a trace of atmosphere, which slowly lowers its orbit, and every few weeks it fires its engines to climb back up. Each of these changes shifts future passes by seconds or minutes, so a prediction a week ahead is a guide and the one for tonight is close to exact. Check again on the day; the catalogue is rebuilt four times daily.
Tiangong and Hubble too
The pass panel also predicts the Chinese space station Tiangong and the Hubble Space Telescope. Tiangong orbits at a similar height to the ISS but at a 41.5° tilt, so it is easiest to see from mid-latitudes. Hubble flies higher and stays within 28.5° of the equator, which is why it rarely clears the horizon for observers in northern Europe and Canada. Select any other satellite on the globe to calculate its passes the same way.
Where the data comes from
Orbits come from the public General Perturbations (GP) catalogue published by Space-Track.org for the US Space Force, cross-checked against an independent set from CelesTrak before each release ships. A new release is built four times a day.
Each release is signed with Ed25519 - the same signed catalogue the Orbit Map apps download. Your browser checks that signature and the SHA-256 of every byte before drawing anything, then runs the SGP4/SDP4 model itself. Nothing about what you search for, or where you are, is sent back.
Public GP elements propagated for education. Accuracy degrades with element age. Not for conjunction assessment, navigation or antenna pointing. Earth imagery: NASA Blue Marble and Black Marble. City list: GeoNames, CC BY 4.0.