Frequently asked questions

Check the 'Next visible ISS pass' card on your city page. At the start time, face the 'appears' direction: the station looks like a bright, steady, non-blinking star moving smoothly across the sky for a few minutes. It's only visible near dusk and dawn, when it's sunlit and your sky is dark.

From the station's latest orbital elements published by CelesTrak, refreshed nightly. We count a pass as visible when the ISS is sunlit, the Sun is at least 6 degrees below your horizon and the station climbs at least 10 degrees. Orbit boosts can shift times by a minute or more, so re-check on the day.

Visibility depends on the station being lit by the Sun while you're in darkness. For several days at a time the geometry doesn't work for a given city, so there are no visible passes, then they return.

Fewer than the ZHR. That number assumes a perfectly dark sky with the radiant overhead. From a dark rural site with the Moon down you might see a third to half of it; from a city, a handful an hour at best.

They're rough. We combine distance to an assumed typical ascent track, whether your sky is dark, and whether the rocket is in sunlight. We don't model clouds, terrain, light pollution or each mission's exact trajectory. Treat 'likely' as 'worth stepping outside', not a promise.

Many launches are listed with only a target date or month. We only estimate visibility once a launch time is published to the hour or better.

Each launch page shows a compass for every city. The mint arrow points to where the rocket first rises above about 3 degrees; the amber arc shows the direction it travels. Headings assume typical trajectories for that pad and orbit.

A twilight launch whose exhaust plume is lit by the Sun high above a dark sky, creating a glowing, expanding cloud visible for hundreds of miles.

Only near the launch site, and mainly when the booster flies back to land on shore. Drone-ship landings at sea don't produce booms on land.

Most US cities need a strong geomagnetic storm. We estimate the Kp index needed for your city and compare it to NOAA's forecast for tonight's dark hours. Phone cameras can pick up aurora your eyes can't.

Nightly, with space weather refreshed more often when run on a schedule. Launch times can change at any time, so check the provider's official channels before you go.

Launch schedules from The Space Devs' Launch Library 2, and space weather (Kp index and 3-day forecast) from NOAA's Space Weather Prediction Center.