The Moon in full detail, every planet that is up, double stars, the brighter clusters, and almost no galaxies. Light pollution barely touches bright objects and removes faint extended ones almost entirely.
The honest answer divides sharply by the kind of object, and knowing which side a target falls on saves a great deal of frustration.
What a city sky barely affects
The Moon, every planet, double stars and the brighter star clusters. These are concentrated sources: the sky background rises, but they are so much brighter than it that the difference is small.
What it removes
Faint extended objects — galaxies, large nebulae, the Milky Way itself. Their surface brightness competes directly with the background, and when the background rises they simply vanish.
What actually helps
A darker spot rather than a darker filter. Getting out of direct sight of street lamps, observing from a shaded corner, and letting the eyes adapt for twenty minutes without a phone screen each do more than most purchases.
Sorting a target list by sky
Keep a list by object type. City nights are for the Moon, planets and doubles; the drive out of town is for everything else. Planning that way means every clear night is usable rather than half of them being disappointing.
The questions that keep arriving
Is a telescope worth owning in a city at all?
For the Moon and planets, entirely. They are bright enough that the sky background is irrelevant, and a balcony in a city centre is as good a place to look at Saturn as a field in the countryside.
Will a filter fix it?
For emission nebulae, partly. For galaxies and star clusters, no — they shine across the whole spectrum and a filter dims them along with the sky.
Last reviewed 17 September 2026