Light Pollution
Light pollution is artificial light — from cities, towns and roadways — scattering upward and brightening the night sky, washing out faint astronomical detail like the Milky Way's core long before the effect is obvious to the naked eye. A sky that looks reasonably dark to a casual glance can still carry enough light pollution to significantly wash out a long-exposure astrophotograph.
Genuinely dark skies suitable for serious astrophotography usually mean getting well outside urban and suburban light domes, often 30 to 60 minutes' drive from a mid-sized city depending on local geography. Light-pollution maps, widely available online, let photographers check a location's darkness in advance rather than discovering the problem after arriving. No amount of camera settings optimization compensates fully for a genuinely light-polluted sky.
Frequently Asked Questions
Can I remove light pollution's effect in post-processing?
Partially — dedicated light-pollution-filter software and gradient removal tools can reduce the washed-out sky glow somewhat, but they can't fully recover the faint detail a genuinely dark sky would have captured directly.
Does the moon count as a source of light pollution?
Functionally, yes, for astrophotography purposes — a bright moon washes out the same faint sky detail artificial light pollution does, which is why serious Milky Way photographers plan shoots around new-moon periods specifically.