GUIDES / OBSERVING
Light pollution and seeing satellites
By Jeroen Wouda · 2 November 2026 · Observing
Light pollution is usually discussed as a loss: the Milky Way gone, the faint stars gone, a sky reduced to a dozen points. For satellite spotting the picture is more specific. City glow takes away a great deal, but it does not take away a bright pass, and understanding where the limits actually fall makes the difference between a frustrating evening and a reliable habit.
What it hides and what it does not
Light pollution raises the background brightness of the sky. Anything fainter than that background disappears, which is why a suburban sky shows a few hundred stars where a dark site shows thousands.
The station at its brightest is nowhere near that threshold. It is brighter than any star, so a bright overhead pass remains obvious from a lit street, a courtyard or a balcony in the middle of a city. If you have been told that you need to travel to the countryside to see the space station, that is not correct.
The losses are at the margins. A low pass with an unfavourable phase angle can be a modest star at the best of times; add city glow and it becomes invisible. Most of what you lose to light pollution is the long list of mediocre passes, not the good ones. Learning to pick the good ones is the practical response.
Twilight is the real constraint
A satellite is visible only when two conditions hold at once: it is in sunlight, and your sky is dark enough to show it. That overlap is short. After sunset the sky darkens over roughly an hour and a half, while the station, 400 kilometres up, stays sunlit for a while longer and then enters the Earth's shadow.
The usable window therefore sits in twilight, and twilight is exactly when the sky is brightest. In practice this matters more than the streetlights. A bright pass at the end of twilight is easy; the same pass an hour later may not happen at all, because the station is in shadow.
Local light beats general glow
A lamp in your field of view is worse than a city on the horizon. Scattered light inside your eye reduces contrast across everything you are looking at, and a single unshaded streetlight twenty metres away does more damage than the general glow of a town.
The fix is positioning, not equipment. Stand so that the nearest lamp is behind a wall, a hedge or your own shoulder. Look out over darker ground rather than towards a lit car park. A doorway, the shadowed side of a building, or the far end of a garden can be enough.
Direction matters too. Sky brightness is not uniform: it is greatest towards the densest lighting, usually the town centre or a retail park. A pass low in that direction is harder than the same pass over open fields.
Give your eyes time
Adaptation is slow and easily undone. Ten to twenty minutes in dim light will noticeably improve what you can see; a glance at a phone screen at full brightness resets much of that. If you need light, use a red torch or set the phone to its lowest brightness, and keep it brief.
This matters less for the brightest passes, which you could spot while walking under streetlights, and more for the marginal ones, where the difference between seeing and not seeing is small.
The moon counts as light pollution
A bright moon lifts the background sky across the whole sky, not just near the moon. Around full moon, faint passes that would be easy on a dark night become genuinely difficult. If you are choosing between two passes on different nights, the phase of the moon is worth a glance.
What this means in practice
- Prefer passes with a high maximum elevation and a bright magnitude estimate; those survive city skies.
- Face away from the nearest lamp, and put a wall between you and it if you can.
- Give your eyes ten minutes, and keep the phone in your pocket.
- Treat twilight as the working window rather than an inconvenience.
None of this requires dark skies. It requires knowing which passes are worth going out for, and standing in the right place when they happen.
A note on other satellites
The station is the easy case because it is large and bright. Smaller satellites, including the many craft now in low orbit, are a different matter: from a city most of them are simply below the threshold, and from a dark site they become visible as slower, fainter points. If you find yourself enjoying the hunt, a darker location genuinely does open up more of the sky, even though the station itself does not need it.
Where to go next
- ISS pass tables list elevation and brightness, which is what you need to pick a pass that survives your sky.
- Space station sightings in winter explains why the best evening windows fall in the darker half of the year.
- Spotting the ISS from a balcony or small garden covers positioning when your sky is limited.
More guides
- What the ISS actually looks like from the ground — Why the space station is a point of light rather than a shape, and why its brightness changes from one pass to the next.
- Space station sightings in winter — Early sunsets and long dark evenings make winter the best season for evening passes. What changes, and what to wear.
- Spotting the ISS from a balcony or a small garden — No telescope, no dark sky and no big garden needed. A workable method for seeing passes from a small, obstructed space.