About ISS Live Tracker
ISS Live Tracker (isstrackerlive.space) is a free website that shows where the International Space Station is right now and predicts when you can see it from your own location. It also tracks China’s Tiangong station, the Hubble Space Telescope and the NOAA-19 weather satellite, and adds companion tools: the live crew manifest, space weather, satellite close approaches and an ISS transit calculator. It runs in the browser, needs no account, and can be installed as a web app.
Who builds it
The site is designed, built and maintained by Afin Nafsan as an independent project. It is not affiliated with, endorsed by or operated by NASA, Roscosmos, ESA, JAXA, CSA, CNSA or any other space agency. Agency names appear only to identify data sources and the organisations behind the missions described.
Where the data comes from
Nothing on the site is hand-entered. Every number comes from one of the public sources below, and is either shown directly or fed into a calculation described in the next section.
| Source | Used for | Refresh |
|---|---|---|
| CelesTrak | Two-line orbital elements (TLEs) for every tracked satellite; SOCRATES close-approach screening | Elements fetched on demand and cached for minutes; SOCRATES recomputed a few times a day |
| NOAA Space Weather Prediction Center | Kp index and forecast, OVATION aurora oval, GOES X-ray flux | Every 5 to 10 minutes |
| astroviewer / corquaid people-in-space feed | Crew names, agencies, vehicles, launch dates, current Expedition (with Open Notify as a fallback) | Cached for a few minutes |
| Open-Meteo | Hourly cloud-cover forecast; city search | Hourly forecast, cached for 30 minutes |
| The Space Devs (Launch Library 2) | Upcoming rocket launches | Cached for 15 minutes |
| Where the ISS at? | Backup live position if orbital elements are unavailable | Live |
| satellite.js and Astronomy Engine | SGP4 orbit propagation; Sun and Moon positions (both open source) | Run in your browser |
How positions and pass times are calculated
For each satellite the site downloads a TLE: a compact set of numbers describing its orbit at a particular moment, called its epoch. The open-source SGP4 model then propagates that orbit forward or backward to any time you ask about, which gives the satellite’s latitude, longitude and altitude. The calculation runs in your own browser, so the map position updates every second without contacting a server. The guides What is a TLE?, What is SGP4? and How ISS tracking works explain this in detail.
A pass is a period when the satellite is above your horizon. A pass counts as visible only when two conditions hold at its peak: the satellite is in direct sunlight, and the Sun is more than 6 degrees below your horizon, so the sky is dark enough to see it. That is why visible ISS passes happen around dawn and dusk and never in the middle of the night. The same rule is used on the pass list, the city pages and the pass alerts, so they cannot disagree. See why the ISS is visible for the physics.
How accurate is it?
- Position and pass times. With fresh orbital elements, positions are typically accurate to a few kilometres and pass times to within seconds to a minute or two. Accuracy declines as the elements age, and the ISS occasionally changes orbit during reboosts, so a pass forecast several days out is less certain than tonight’s.
- Brightness estimates. The magnitude shown for an ISS pass comes from a standard brightness model and is good to roughly one magnitude. We checked it against Heavens-Above for six passes over Sydney, and it agreed to within 0.1 to 0.8 magnitudes.
- Transit predictions. The ground path of an ISS transit of the Sun or Moon is only about 5 to 15 km wide, so predictions are provisional until a day or two beforehand and should be re-run close to the event.
- Close approaches. The conjunction page shows screening results from public data, which are worst-case bounds and not operational collision warnings.
- Space weather. Shown for information only; for operational warnings use NOAA directly.
- Cloud cover. A forecast for your area, not a guarantee of what you will see.
Editorial approach and corrections
Guides are written to explain how the tracker works and to answer practical questions about seeing and understanding the station. Live pages state their data source and show when the data was last refreshed. Where a source has proved unreliable we say so and work around it: for example, crew time-in-orbit is calculated from launch dates rather than copied from a feed whose own counter was found to be wrong.
If you find an error, an out-of-date fact or a broken page, please email afinnafsan@gmail.com. Corrections are made as soon as they are verified.
How the site is funded
The site is free to use. It is supported by voluntary donations through Buy Me a Coffee and may display advertising. Advertising never affects predictions or the content of guides. See the privacy policy for what data is stored and how.
What’s new
- A free embeddable ISS map widget for other websites.
- “What’s in the sky tonight”: twilight times, Moon phase, visible planets and ISS passes for your location.
- Live crew manifest and Expedition tracker, a space-weather dashboard with an aurora overlay on the map, and a satellite conjunction watch.
- ISS transit calculator for the Sun and Moon, estimated brightness for ISS passes, a map time scrubber, and a personal sighting log.
- “Best pass this week” highlight, upcoming launches, a QR link to the AR sky finder and a shareable position card.
Ready to see it in action? Open the live map, or find out whether the station is visible from where you are tonight.
Open the live tracker Is the ISS visible tonight?