# Light Pollution Map

> Light Pollution Map is an interactive web application that displays global light pollution data using the Bortle Scale and SQM measurements, helping users find optimal locations for stargazing, Milky Way viewing, and aurora observation. Now featuring real-time aurora probability forecasts, advanced exposure calculators, comprehensive weather data, and support for 21 languages including newly added Danish, Swedish, Finnish, and Hebrew.

## Overview

Light Pollution Map (lightpollutionmap.app) provides a comprehensive, interactive visualization of global light pollution data. The map utilizes the Bortle Scale and Sky Quality Meter (SQM) measurements to help astronomy enthusiasts, photographers, and nature lovers identify optimal locations for stargazing and astrophotography.

The application combines satellite data from NOAA's VIIRS with user-friendly map interfaces to display light pollution levels worldwide. Users can search for specific locations, obtain detailed information about night sky quality, plan their stargazing activities, calculate exposure times for astrophotography, monitor aurora activity, and access comprehensive weather data for optimal observation planning.

## Key Features

### Interactive Map Interface

The core of the application is an interactive map that displays light pollution data using color-coded overlays. Users can:

- Pan and zoom to explore different regions with smooth continuous zoom functionality
- Toggle between different base maps (Dark, Satellite, Streets)
- Adjust the opacity of the light pollution overlay with dedicated controls
- Search for specific locations using the built-in geocoder with search history
- View historical light pollution data from 2006 to 2024 with trend analysis
- Toggle day/night terminator to see which parts of the world are currently dark
- View certified Dark Sky Places worldwide with detailed information
- Monitor real-time aurora probability with NOAA data integration (BETA)
- Access comprehensive weather data including cloud cover, temperature, and air quality
- View current lunar phase information with rise/set times
- Calculate exposure times for astrophotography based on light pollution levels
- Embed interactive maps on external websites using customizable widgets

### Bortle Scale Integration

The Bortle Scale is a nine-level numeric scale that measures the night sky's brightness of a particular location. The scale ranges from Class 1 (excellent dark-sky sites) to Class 9 (inner-city skies). On our map:

- Class 1-2 (Dark blue): Excellent dark skies with minimal light pollution
- Class 3-4 (Green): Rural to rural/suburban transition areas
- Class 5-6 (Yellow): Suburban skies
- Class 7-9 (Red/White): Urban/city skies with significant light pollution

### Location Details

When users click on a specific location, the application provides detailed information:

- Precise latitude and longitude coordinates
- Bortle Scale classification for the selected point (displayed with 1 decimal precision)
- SQM (Sky Quality Meter) value in magnitude per square arcsecond (displayed with 2 decimal precision)
- Milky Way visibility assessment with detailed descriptions
- Estimated number of visible stars based on light pollution levels
- Historical light pollution data (2006-2024) with interactive trend visualization and predictions
- Information about certified Dark Sky Places (if applicable)
- Real-time aurora probability with activity level indicators
- Comprehensive weather data including nighttime conditions, cloud cover, and air quality (AQI)
- Current lunar phase information with rise/set times and illumination percentage
- Artificial brightness ratio compared to natural sky brightness
- Location sharing capabilities with direct URL links

### Multi-language Support

The website is available in 21 languages with complete translations including all new features:
- English (default): https://lightpollutionmap.app/
- Spanish (Español): https://lightpollutionmap.app/es/
- Japanese (日本語): https://lightpollutionmap.app/ja/
- Polish (Polski): https://lightpollutionmap.app/pl/
- German (Deutsch): https://lightpollutionmap.app/de/
- Italian (Italiano): https://lightpollutionmap.app/it/
- French (Français): https://lightpollutionmap.app/fr/
- Norwegian (Norsk bokmål): https://lightpollutionmap.app/nb/
- Danish (Dansk): https://lightpollutionmap.app/da/ - NEW
- Swedish (Svenska): https://lightpollutionmap.app/sv/ - NEW
- Finnish (Suomi): https://lightpollutionmap.app/fi/ - NEW
- Russian (Русский): https://lightpollutionmap.app/ru/
- Turkish (Türkçe): https://lightpollutionmap.app/tr/
- Korean (한국어): https://lightpollutionmap.app/ko/
- Dutch (Nederlands): https://lightpollutionmap.app/nl/
- Portuguese (Português): https://lightpollutionmap.app/pt/
- Romanian (Română): https://lightpollutionmap.app/ro/
- Hungarian (Magyar): https://lightpollutionmap.app/hu/
- Ukrainian (Українська): https://lightpollutionmap.app/uk/
- Traditional Chinese (繁體中文): https://lightpollutionmap.app/zh-tw/
- Arabic (العربية): https://lightpollutionmap.app/ar/
- Hebrew (עברית): https://lightpollutionmap.app/he/ - NEW

The language picker features an optimized interface with search functionality for desktop users and a compact design for mobile devices, making it easy to switch between languages.

#### Intelligent Chinese Language Detection
The website includes advanced language detection specifically optimized for Chinese users:
- Automatically detects all Chinese language variants (zh-cn, zh-tw, zh-hk, zh-mo, zh-sg, zh-hans, zh-hant)
- Suggests switching to Traditional Chinese (繁體中文) for users with any Chinese browser language setting
- Provides localized prompts in the user's detected language
- Covers users from Mainland China, Taiwan, Hong Kong, Macau, Singapore, and other Chinese-speaking regions
- Ensures no Chinese-speaking user misses the Traditional Chinese version of the website

### Dark Sky Places

The map highlights International Dark Sky Places, which are locations certified for their exceptional starry nights and protected nocturnal environments. Users can:

- View all certified Dark Sky Places worldwide
- See details about each location including certification year, type, and area
- Find the nearest Dark Sky Place to their location

### Aurora Probability Forecasting (BETA)

The application now includes real-time aurora probability forecasting using NOAA data:

- Live aurora probability visualization with color-coded intensity levels
- Activity level indicators (Low, Moderate, High)
- Forecast time information with regular updates
- Dedicated opacity controls for aurora layer visualization
- Integration with location details showing local aurora probability

### Exposure Calculator for Astrophotography

A comprehensive tool for astrophotography planning:

- Calculate equivalent exposure times based on light pollution levels
- Support for both Bortle Scale and SQM value inputs
- Auto-fill functionality using current location data
- Real-time calculations with detailed explanations
- Exposure multiplier information for different conditions
- Helpful examples and guidance for beginners

### Weather Integration

Comprehensive weather data specifically tailored for astronomy:

- Nighttime weather conditions with temperature ranges
- Cloud cover percentage for clear sky assessment
- Air Quality Index (AQI) with detailed level descriptions
- Visibility measurements for atmospheric clarity
- Historical weather data (yesterday, today, next 5 days)
- Collapsible interface to save screen space
- Weather source attribution and update timestamps

### Lunar Phase Information

Detailed moon phase data for observation planning:

- Current lunar phase with visual representation
- Moon age in days and illumination percentage
- Moonrise and moonset times in local timezone
- Moon altitude and distance information
- Next phase predictions with dates
- Hemisphere-specific moon orientation
- Observer coordinates and timezone information

## Technical Implementation

The web application is built using:

- Astro.js as the core framework
- Leaflet.js for map rendering and interaction
- Chart.js for data visualization and trend analysis
- Tailwind CSS for responsive UI components
- Custom components for UI elements

The light pollution layer comes from David Lorenz. It is calculated using a model of atmospheric light transfer and scattering. The light sources in the model come from annual average cloud-free nighttime lights processed and produced by the Earth Observation Group at the Colorado School of Mines. The raw light data comes from NOAA's VIIRS (Visible Infrared Imaging Radiometer Suite) satellite imagery.

## FAQ

### Is this website updated in real-time? How often is the data refreshed?

The website's data is updated periodically. The light pollution layer comes from David Lorenz. It is calculated using a model of atmospheric light transfer and scattering. The light sources in the model come from annual average cloud-free nighttime lights processed and produced by the Earth Observation Group at the Colorado School of Mines, which is typically updated annually. The raw light data comes from NOAA's VIIRS satellite. We plan to incorporate additional data sources in the future.

### What does "Bortle Scale" on the map mean? How should I interpret it?

The Bortle Scale is a standard measurement of night sky darkness, used as an indicator for stargazing. It ranges from Class 1 (absolute darkness) to Class 9 (severe light pollution). The lower the scale number, the more stars you can see. The map uses color coding to differentiate between Bortle classes, helping you quickly determine the darkness level of the night sky in any location.

### What is "SQM" and how does it differ from the Bortle Scale?

SQM (Sky Quality Meter) represents night sky brightness in numerical form, measured in mag/arcsec². Higher numbers indicate darker skies. While the Bortle Scale is a classification system, SQM provides precise numerical values. SQM measurements can be converted to Bortle Scale classes for easier interpretation.

### How can I find the best stargazing locations near me?

Our system analyzes your approximate location based on your IP address and automatically displays the Bortle class for that area. You can also search for specific addresses or manually explore the map to discover optimal stargazing spots in other regions.

### Can the map show aurora activity? Are there recommended regions for aurora viewing?

Yes! We now feature a real-time aurora probability layer (BETA) that displays aurora forecasting data from NOAA. The layer shows probability levels from 10% to 90%+ with color-coded visualization. Users can toggle the aurora layer on/off and adjust its opacity for optimal viewing. This feature is particularly useful for users in high-latitude regions like Northern Europe, Canada, and Alaska to track and pursue aurora sightings. The aurora data includes activity level indicators (Low, Moderate, High) and forecast timestamps.

### Can I use this to plan Milky Way photography sessions?

Absolutely! The map combines light pollution levels with geographical data to help you locate ideal spots for Milky Way observation and photography. We now include an advanced Exposure Calculator that helps determine optimal exposure times based on light pollution conditions. The calculator supports both Bortle Scale and SQM inputs, provides auto-fill functionality using your current location, and offers detailed explanations of exposure multipliers. Additionally, the integrated weather data shows cloud cover, atmospheric conditions, and lunar phase information - all crucial factors for successful astrophotography planning.

### Is this map optimized for mobile use? Is there an app version?

Our website is fully optimized for mobile devices, providing a smooth experience. You can also check stargazing conditions and light pollution information through the StargazingHub App, available for both iOS and Android devices. Additionally, the Super Moon App provides advanced lunar phase tracking and moon observation planning features.

### Which countries or regions are supported? Is it a global map?

Yes, lightpollutionmap.app provides a global light pollution map covering most countries and regions worldwide. It's suitable for astronomy enthusiasts and travelers around the globe. We also offer a Chinese version of the website at Darkmap.cn.

### What's the source of the light pollution data? Is it reliable?

Our data is primarily based on NOAA's VIIRS, and the light pollution map is created by David Lorenz. We'll soon provide light pollution data from the World Atlas 2015, sourced from research by Falchi, Fabio et al.

### How can I share a specific location on the map?

You can go directly to a specific spot by adding coordinates to the URL: `https://lightpollutionmap.app/?lat=25.3125&lng=-80.6875&zoom=8`
Use this to share locations or bookmark your favorite stargazing places. Just change the latitude (lat), longitude (lng), and zoom level.

### Is there a user community or feature for uploading observation reports?

We're planning to build a community for stargazing enthusiasts where users can upload field observation reports, photos, and suggestions. This will enrich our map data and allow users to share their observation experiences.

### Is there a fee for using this service? What premium features are available?

Our website's basic features are permanently free to use. Currently, we don't have plans for a membership program, so you can use our light pollution map with confidence.

### How can beginners get started with night sky observation? How does the map help?

The map helps stargazers quickly find suitable observation locations nearby and provides Bortle class information along with basic astronomical guidance. We plan to expand beginner tutorials and observation recommendations in the future to help you easily start your stargazing journey.

### How can I reduce the impact of light pollution on astronomical observations?

To minimize the effects of light pollution on your astronomical observations, we recommend using Light Pollution Filters. These specialized filters can significantly improve visibility by blocking specific wavelengths of artificial light while allowing starlight to pass through. For quality options, check out Optolong Light Pollution Filters, which offer solutions for both visual observation and astrophotography.

### How does the Exposure Calculator work for astrophotography?

The Exposure Calculator helps determine equivalent exposure times based on light pollution conditions. You can input either Bortle Scale values (1-9) or SQM measurements (15-22 mag/arcsec²). The calculator uses your reference exposure time (typically from a Bortle 1 location) and calculates how much longer you need to expose in your current location to achieve similar image quality. For example, a 1-hour exposure at Bortle 1 might require 9.8 hours at Bortle 5. The tool includes auto-fill functionality using your current location data and provides detailed explanations of the calculations.

### What weather information is available for astronomy planning?

The website now includes comprehensive weather data specifically tailored for astronomical observations. This includes nighttime temperature ranges, cloud cover percentages, air quality index (AQI) with detailed level descriptions, visibility measurements, and historical weather data covering yesterday, today, and the next 5 days. The weather data is sourced from Open-Meteo and updates regularly. The interface is collapsible to save screen space and includes weather source attribution with update timestamps.

### How accurate is the aurora probability forecasting?

The aurora probability layer (currently in BETA) uses real-time data from NOAA to provide aurora forecasting. The visualization shows probability levels from 10% to 90%+ with color-coded intensity levels and activity indicators (Low, Moderate, High). The data includes forecast timestamps and is updated regularly. While this feature is particularly useful for high-latitude regions, aurora visibility also depends on local weather conditions, light pollution levels, and magnetic field activity, so it should be used in conjunction with other aurora forecasting tools.

### Can I embed the light pollution map on my website?

Yes! The website now supports embeddable widgets that can be integrated into external websites. You can generate custom embed codes using either iframe or JavaScript options. The embed generator allows you to choose from preset sizes (Small 400×300, Medium 600×400, Large 800×600) or create custom dimensions. The embedded maps preserve the current location, zoom level, and active layers, and support all available languages. The embedded version features a simplified UI optimized for integration while maintaining full functionality.

### What languages are supported and how does language detection work?

The website supports 21 languages with complete translations of all features. The system includes intelligent language detection that automatically identifies users' preferred languages based on their browser settings. For Chinese users specifically, the system detects all Chinese language variants (including Simplified Chinese from Mainland China and Singapore, Traditional Chinese from Taiwan, Hong Kong, and Macau) and suggests switching to the Traditional Chinese version. For Arabic users, the system provides complete RTL (right-to-left) text direction support with proper Arabic localization. This ensures that users from any region can easily access the website in their preferred language and script. Users can also manually switch languages using the language picker, which features an optimized interface with search functionality.

## Related Resources

- [International Dark-Sky Association](https://www.darksky.org/): Organization working to preserve dark skies
- [Globe at Night](https://www.globeatnight.org/): Citizen-science program for monitoring light pollution
- [NASA Night Sky Network](https://nightsky.jpl.nasa.gov/): Astronomy outreach and education resources
- [StargazingHub website](https://laysky.com/): Astronomers' forecast for observing conditions
- [StargazingHub iOS App](https://apps.apple.com/app/id1478601599): Mobile application for checking stargazing conditions and light pollution information
- [StargazingHub Android App](https://play.google.com/store/apps/details?id=com.laysky.stargazinghub): Android version of the StargazingHub mobile application
- [Super Moon App](https://apps.apple.com/app/id1234567890): Advanced lunar phase tracking and moon observation planning app

## Available Versions

All versions include the complete feature set with aurora forecasting, exposure calculator, weather integration, and lunar phase information:

- [Light Pollution Map (English)](https://lightpollutionmap.app/): The main English version of the application
- [Light Pollution Map (Spanish)](https://lightpollutionmap.app/es/): Spanish language version (Español)
- [Light Pollution Map (Japanese)](https://lightpollutionmap.app/ja/): Japanese language version (日本語)
- [Light Pollution Map (Polish)](https://lightpollutionmap.app/pl/): Polish language version (Polski)
- [Light Pollution Map (German)](https://lightpollutionmap.app/de/): German language version (Deutsch)
- [Light Pollution Map (Italian)](https://lightpollutionmap.app/it/): Italian language version (Italiano)
- [Light Pollution Map (French)](https://lightpollutionmap.app/fr/): French language version (Français)
- [Light Pollution Map (Norwegian)](https://lightpollutionmap.app/nb/): Norwegian language version (Norsk bokmål)
- [Light Pollution Map (Danish)](https://lightpollutionmap.app/da/): Danish language version (Dansk) - NEW
- [Light Pollution Map (Swedish)](https://lightpollutionmap.app/sv/): Swedish language version (Svenska) - NEW
- [Light Pollution Map (Finnish)](https://lightpollutionmap.app/fi/): Finnish language version (Suomi) - NEW
- [Light Pollution Map (Russian)](https://lightpollutionmap.app/ru/): Russian language version (Русский)
- [Light Pollution Map (Turkish)](https://lightpollutionmap.app/tr/): Turkish language version (Türkçe)
- [Light Pollution Map (Korean)](https://lightpollutionmap.app/ko/): Korean language version (한국어)
- [Light Pollution Map (Dutch)](https://lightpollutionmap.app/nl/): Dutch language version (Nederlands)
- [Light Pollution Map (Portuguese)](https://lightpollutionmap.app/pt/): Portuguese language version (Português)
- [Light Pollution Map (Romanian)](https://lightpollutionmap.app/ro/): Romanian language version (Română)
- [Light Pollution Map (Hungarian)](https://lightpollutionmap.app/hu/): Hungarian language version (Magyar)
- [Light Pollution Map (Ukrainian)](https://lightpollutionmap.app/uk/): Ukrainian language version (Українська)
- [Light Pollution Map (Traditional Chinese)](https://lightpollutionmap.app/zh-tw/): Traditional Chinese language version (繁體中文)
- [Light Pollution Map (Arabic)](https://lightpollutionmap.app/ar/): Arabic language version (العربية)
- [Light Pollution Map (Hebrew)](https://lightpollutionmap.app/he/): Hebrew language version (עברית) - NEW
- [Dark Map (Chinese)](https://www.darkmap.cn/): Chinese language version with similar functionality
- [StargazingHub iOS App](https://apps.apple.com/app/id1478601599): Mobile application for iOS devices
- [StargazingHub Android App](https://play.google.com/store/apps/details?id=com.laysky.stargazinghub): Android version of the StargazingHub mobile application
- [Super Moon App](https://apps.apple.com/app/id1234567890): Advanced lunar phase tracking and moon observation planning app

### Embeddable Widgets

The application now supports embeddable widgets for external websites:
- [Embed Generator](https://lightpollutionmap.app/): Create custom embeddable maps with iframe or JavaScript options
- Responsive sizing options (Small 400×300, Medium 600×400, Large 800×600, Custom)
- Preserves current location, zoom level, and active layers
- Multilingual support in embedded versions
- Simplified UI optimized for embedding