Dark Window
Your deep sky companionYour deep sky imaging companion
ISS pass finder
When the International Space Station crosses your sky over the next several days, and which passes are bright enough and dark enough to see.
Nothing is sent anywhere: the math runs in your browser. Times use your device’s clock and time zone.
- Go out a few minutes early and let your eyes adjust. A pass peaking above 40 degrees is the easiest to enjoy.
- Face the rise direction, then follow it across. It fades out as it enters Earth’s shadow, sometimes high in the sky.
- Clouds matter: check the planner for cloud cover at that hour.
- Why are most passes not visible?
- The ISS shines only by reflected sunlight. To see it, your sky must be dark (Sun at least 6 degrees below the horizon) while the station, 400 km up, is still in sunlight. That happens in the hour or two after dusk and before dawn. Passes in full daylight, or in the middle of the night when the station is in Earth's shadow, cannot be seen.
- How accurate are the times?
- Good to about a minute for the next few days, using the station's latest published orbit. The ISS occasionally fires its engines to adjust its orbit, which can shift later passes, so check again the day before.
- Which way do I look?
- The page gives the compass direction where it rises, the direction and height at its highest point, and where it sets. A fist held at arm's length is about 10 degrees, so a 60 degree peak is nearly overhead. It moves steadily across the sky in 3 to 6 minutes and never blinks, unlike an aircraft.
- Can I photograph it?
- Yes. A 10 to 30 second exposure on a wide lens catches it as a bright streak. Through a telescope or long lens it crosses the frame in a second, so streaks in your deep-sky subs from a pass near your target are normal; stacking with outlier rejection removes them.
Open the Dark Window planner to check the weather for tonight.
Support Dark WindowFree, no ads. A tip covers hosting and keeps updates coming.