How to use the satellite tracker
- Use the checkboxes at the top to choose which groups of satellites to show. At first the Space stations group, which includes the International Space Station (ISS), is on.
- The moving dots on the map are satellites. Hover over a dot to see its name and altitude, and click it to select that satellite.
- The selected satellite’s path is drawn as a green line. The dim part is where it has been, and the bright part is where it is going.
- Under “Pass prediction location”, pick a city or press “Use my location” to see when that satellite crosses your sky in the next 48 hours.
- Raise the time speed to 10x, 60x or 600x to see how orbits unfold quickly, and press “Now” to return to the present.
How satellite positions are calculated
A satellite’s position is calculated from a set of numbers called orbital elements. They describe the tilt and shape of the orbit and how many times a day the satellite circles the Earth, and sites such as CelesTrak publish them based on tracking by the U.S. Space Force. Your browser downloads the elements from CelesTrak and calculates the current position itself using a standard method called SGP4. All of the calculation happens on your device.
The elements are updated about every two hours, and this page keeps the same data in your browser for two hours before using it again. Because of atmospheric drag and orbit adjustments, satellites drift a little from their plan, so the older the data, the larger the gap between the calculated and real position. The age of the oldest data is shown above the map.
Types of orbit and how they look on the map
- Low Earth orbit (about 160 to 2,000 km): the ISS travels at about 7.7 km per second at roughly 400 km and circles the Earth about every 90 minutes. On the map it moves quickly and traces a wave-shaped path.
- Medium Earth orbit (about 2,000 to 35,000 km): GPS satellites circle in about 12 hours at roughly 20,000 km. They move slowly.
- Geostationary orbit (about 36,000 km): one lap takes 24 hours, the same as the Earth’s rotation, so the satellite appears to stand still over one spot. Weather and communications satellites such as GEO-KOMPSAT sit here and barely move on the map.
Orbits look wavy because the Earth rotates beneath a satellite that follows a steady path around it. The greater the tilt of the orbit, the farther toward the poles it reaches. The ISS is tilted about 51.6 degrees, so its path peaks near that latitude.
Reading the night map and the day/night line
The background is the Earth at night. Clusters of city lights mark places with dense population and industry, and dark areas are oceans, deserts and sparsely populated regions. This background is an average image made from satellite observations, so it does not show the lights of this very moment.
With “Day/night line” on, the side currently lit by the Sun is covered in blue, and the yellow dot marks the point where the Sun is directly overhead. Near the edge it is sunrise or sunset right now. A satellite that enters Earth’s shadow also stops reflecting sunlight and cannot be seen with the naked eye.
How to see a satellite with the naked eye
The easiest satellite to see is the International Space Station. The best time is just after sunset or just before sunrise, when the sky is dark where you are but sunlight still reaches the height of the satellite. The green rows in the pass table are those times. The higher it climbs, the easier it is to see, while near the horizon it is easily blocked by buildings and trees.
A satellite crosses the sky at a steady speed, much faster than a star, and does not blink. If you see blinking colored lights, it is more likely an aircraft.
Accuracy and limits
- Pass predictions show when a satellite is more than 10 degrees above the horizon and do not check whether it is lit by the Sun.
- For satellites that adjust their orbits, like the ISS, predictions can be well off just after a maneuver.
- If your device clock is wrong, the positions will be wrong. Unless you change the time speed, the tool uses your device clock as it is.
- If the orbital data cannot be loaded, no satellites are shown. This can be due to your network or the data provider’s usage limits, so please try again in a moment.
- Constellations with thousands of satellites, such as Starlink, are left out in consideration of the data provider’s usage policy.
Location and privacy
When you press “Use my location”, your browser asks for permission. If you allow it, your location is used only to calculate pass times and is neither sent to a server nor stored. If you decline, you can still pick a nearby city from the list and use the same feature.
Frequently asked questions
Is the position live?
It is calculated from orbital elements using your device clock. With fresh data it is typically within a few kilometers, and the error grows as the data ages. It is not live tracking data like aircraft positions.
No satellites are showing.
The orbital data may still be loading or may have failed to load. Check the status line above the map and try refreshing in a moment. Some company or school networks block outside addresses.
Why doesn’t the GEO-KOMPSAT satellite move?
A geostationary satellite orbits at the same rate as the Earth’s rotation, so it seems to stay over one spot. It barely moves on the map.
Why is Starlink not included?
Constellations of thousands of satellites are not suited to being downloaded by many visitors at once under the data provider’s usage policy, so they are left out.