01 / LOW EARTH ORBIT
Live SGP4 propagation of the International Space Station against an Earth-fixed coordinate globe, a physically positioned Sun, and its current Earth-centered orbit.
02 / ORBITAL ARCHITECTURE
Inspect NASA’s detailed three-dimensional model of the International Space Station. The model is loaded only when requested so the live tracker remains fast on first visit.
NASA 3D ASSET · 42.43 MB GLTF
Drag to rotate, scroll to zoom, and inspect the station’s assembled structure in NASA’s official viewer.
Model credit: NASA Visualization Technology Applications and Development (VTAD).
NASA MODEL SOURCE ↗03 / YOUR SKY
A station pass is useful only when the station is above your horizon, reflecting sunlight, and your sky is dark enough to provide contrast. These predictions test all three conditions locally in your browser.
OBSERVER LOCATION
Use browser location for a private, device-specific prediction. After you approve it, the coordinates are saved only in this browser so you do not need to approve them on every visit.
NEXT 7 DAYS · YOUR LOCAL TIME
ALLOW LOCATION OR ENTER COORDINATES TO CALCULATE YOUR NEXT VIEWING WINDOWS.
FLYBY SIGNAL / OPTIONAL EMAIL
Choose how early you want to know. Apeira Astra will watch current ISS orbital data and email you only when a qualifying naked-eye flyby is approaching your saved location.
We care about privacy, and we hate spam. We will never sell your email address, share it for advertising, or use it for anything except the ISS notifications you request.
04 / SCIENTIFIC METHOD
Current general-perturbation elements for NORAD 25544 are propagated with SGP4 in the browser. The cyan loop freezes Earth’s orientation to show the station’s closed Earth-centered orbital plane at physical altitude. The optional amber ground track lets Earth rotate beneath the orbit and therefore does not close after one revolution.
The full mathematical horizon-to-horizon flyby is calculated first. The naked-eye segment then requires the Sun to be below civil twilight at the observer, the ISS to remain at least partly sunlit, and station elevation to be at least 10°. Transition times are refined to within 0.25 seconds.
Clouds, haze, terrain, buildings, light pollution, atmospheric refraction, orbit corrections, and station attitude affect real visibility. The exact observer coordinates and orbit epoch used for each batch are shown above; a newer orbit record is explicitly marked as a revision.
ISS orbital elements are provided by CelesTrak from U.S. Space Force tracking data. Station facts and naked-eye viewing guidance are cross-referenced with NASA.