StarCast · Light Pollution Guide

What Is Light Pollution and How to Avoid It for Photography?

Light pollution is artificial light scattering into the atmosphere and reducing sky darkness. For photographers it's the primary obstacle to Milky Way photography — here's what causes it and how to work around it.

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Photography forecast

What Causes Light Pollution and What You Can Do

Light pollution comes from cities, towns, farms, and roads — any artificial light source scatters off particles in the atmosphere and illuminates the sky. The Bortle scale (1–9) measures sky darkness, where 1 is the darkest possible and 9 is a city centre. Most people live under Bortle 6–8.

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The Bortle Scale: Your Darkness Ceiling

Bortle 1–2 is wilderness dark sky. Bortle 3–4 is rural. Bortle 5–6 is suburban. Bortle 7–8 is urban. Bortle 9 is a bright city centre. The galactic core is photographable in Bortle 4, visible naked eye in Bortle 3, and dramatic in Bortle 2. StarCast shows Bortle class for any location you search.

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The Only Fix Is Distance

No filter, no camera setting, and no editing can remove light pollution from images the way driving away from it can. The practical solution is distance — how far you need to drive depends on your city. Most major US cities have Bortle 3 sky within 2–3 hours.

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Shoot Away From the Light Dome

Even in a moderately light-polluted location, the sky is darker in some directions than others. Face away from city glow — the galactic core rises in the south and east, which is often darker than west (where many cities concentrate development). Position light domes behind you or at the frame edge.

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New Moon Helps Even in Higher Bortle

In a Bortle 4–5 location, a new moon night is significantly better than a half moon night. Moon phase has a larger impact on final image quality than moving one Bortle class in many situations. Target new moon in whatever location you can reach.

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StarCast Push Alerts

StarCast shows Bortle class alongside moon phase, transparency, and cloud cover for any location. Save your nearest dark sky location and get a push alert when all four variables align for a high-scoring night. Exclusive to the iOS app.

Common Questions

What is light pollution?

Artificial light scattering into the atmosphere and reducing sky darkness. Measured on the Bortle scale from 1 (darkest) to 9 (brightest city). Most people live under Bortle 6–8 — too bright for meaningful Milky Way photography. StarCast shows Bortle class for any location — free on web.

How do I avoid light pollution for astrophotography?

Drive away from it. Bortle 3 is the practical minimum. Most US cities have Bortle 3 within 2–3 hours. No filter or editing fully compensates for light pollution — distance is the only real fix.

Can you photograph the Milky Way with light pollution?

In Bortle 4, yes — with effort. In Bortle 5–6, the galactic core is faint and requires significant processing. Above Bortle 6, Milky Way photography produces disappointing results regardless of equipment or technique.

What direction has the least light pollution?

Face away from the nearest city. In most of the US, facing south or east is darker than facing west where Atlantic and Pacific coastal cities create horizon glow. The galactic core rises in the south — often the darkest direction from inland locations.

What is LightCast StarCast?

StarCast shows Bortle class and scores night sky conditions — moon phase, transparency, and cloud cover — for any location. Push alerts notify you when conditions are worth the drive. Free on web at lightcastsuite.com/starcast, push notifications in the LightCast iOS app. $2.99/month after a 7-day free trial.

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