Artificial skyglow
Light from cities and other artificial sources scatters through the atmosphere. From an observing site, these contributions can appear as light domes and brighter horizons, including from sources far away.
Light Pollution Simulator
Explore how light pollution changes the night sky from any location on Earth. The DarkSkySites APEX simulator models artificial skyglow using satellite light emissions, atmospheric scattering and local terrain, revealing how nearby cities and distant light sources affect the sky above you.
Choose an observing location to begin.
Search for a place, enter coordinates, or select an example above. The complete APEX controls will appear here.
Observer-centered modeling
What does a light pollution simulator show?
A light pollution map shows where artificial light originates. A skyglow simulator goes further, estimating how that light spreads through the atmosphere and appears from a particular observing location.
DarkSkySites uses satellite-derived light emissions, atmospheric scattering and terrain information to model the distribution of artificial sky brightness across the night sky. The result helps reveal distant light domes, brighter horizons and potentially darker viewing directions.
Atmospheric scattering
APEX models light propagation and scattering through a three-dimensional atmosphere. It is an observer-centered calculation, not simply a blurred light pollution map.
Terrain and viewing direction
Mountains, ridgelines and the observer location affect which light sources contribute to the visible sky. Changing viewing direction reveals how artificial sky brightness varies around the horizon and overhead.
Three views, one modeled sky
Explore the sky in four projections
Hammer-Aitoff
View the celestial dome in an equal-area projection. Compare how skyglow varies across different directions.
360° All-Sky
Explore the complete sky dome from overhead to the horizon in an all-sky projection.
First-Person View
Look around the simulated night sky from ground level, with perspective appropriate to the selected observing location.
Equal-Area Rectangle
Unwrap the full sky into a rectangle. Azimuth is linear horizontally and sine of elevation is linear vertically, preserving equal sky areas.
For developers
Build with DarkSkySites sky brightness data
Integrate modeled light pollution and sky-brightness data into astronomy applications, observing planners, telescope software and other location-based services.
Free API
- Modeled zenith SQM
- SQM-derived Bortle class
- Dataset provenance and quality information
- Geographic lookup by latitude and longitude
Pro API Checking
- Historical sky-brightness analysis
- Directional APEX sky-brightness estimates
- Multiple directions and horizon profiles
Checking current public API configuration.
See the API documentation for current Pro availability and pricing. The API supplies scientific data, not the rendered simulator canvas.
Reference
Light pollution simulator questions
01Can I simulate light pollution anywhere in the world?
Choose a location by place name or latitude and longitude. Worldwide coordinate-based exploration is supported where valid satellite emissions, terrain and simulation data are available. Missing data is reported rather than treated as a dark-sky measurement.
02How accurate is the light pollution simulator?
APEX is a physically motivated model of artificial skyglow, not an exact prediction of what the human eye will see on a particular night. Atmospheric conditions, weather, human vision and modeling limitations affect real-world appearance. Simulated sky brightness is not a live sensor reading.
03What is the difference between a light pollution map and simulator?
A light pollution map describes geographic light emissions or modeled brightness. A skyglow simulator calculates how light from surrounding sources propagates through the atmosphere and appears across the sky from one observer location.
04Can I use DarkSkySites light pollution data in my own application?
Yes. The Free API provides modeled zenith SQM, SQM-derived Bortle class and dataset provenance and quality information for geographic coordinates. Explore the API documentation for current Pro availability, historical analysis and directional sky-brightness capabilities. The data API is not a rendered simulator-canvas endpoint.