The ISS — Reference & Visibility
What the International Space Station is, how it orbits, and why it is visible only around dusk and dawn. Its live position and visible-pass predictions are computed from NASA's own operational ephemeris at /satellites/iss and /satellites/passes; this page is the reference material behind them.
The International Space Station
The International Space Station orbits Earth about every 90 minutes at roughly 400 km altitude, travelling near 28,000 km/h.
The ISS is visible to the naked eye when it catches sunlight against a dark sky — usually within a couple of hours of sunrise or sunset. It appears as a bright, steady 'star' gliding silently across the sky over a few minutes, not blinking like an aircraft. Pass times for an explicit location are computed at /satellites/passes.
Related in the Knowledge Graph
Sources & references
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.