Sources and licenses
Every page on this site is built from open data. This page lists each source, what we use it for and its license. Naming a source does not mean that agency or project endorses this site.
| Data | Source | Used for | License |
|---|---|---|---|
| Kp index (observed, estimated, 3-day forecast), OVATION aurora model, alerts, solar wind, 27-day outlook, solar cycle | NOAA Space Weather Prediction Center (services.swpc.noaa.gov) | Forecasts, Kp, maps, storm and solar wind pages | Public domain (NOAA/NWS disclaimer: may be used without charge for any lawful purpose) |
| Hourly sky cover forecast | National Weather Service API (api.weather.gov) | Clouds on state and city pages | Public domain |
| Kp index since 1932 | GFZ Helmholtz Centre for Geosciences, Geomagnetic Observatory Niemegk (Matzka et al., 2021, doi:10.1029/2020SW002641) | Our count of active nights per year | CC BY 4.0 |
| Place coordinates | U.S. Census Bureau, 2024 Gazetteer files | State and city pages | Public domain |
| Coastlines and borders | Natural Earth, 1:110m | Aurora maps | Public domain |
| Sun, Moon and radiant positions, meteor shower peak times | Astronomy Engine (Don Cross), our calculations | Darkness, Moon, meteor pages | MIT |
| Meteor shower facts (solar longitude of the peak, ZHR, radiant, speed, period) | International Meteor Organization working list (facts only, our text) | Meteor shower pages | Facts, not protected |
| Geomagnetic pole position | IGRF-14 model, published pole for 2025 | Kp needed per place | Public scientific data |
| Font | Manrope, served from our own server | All pages | SIL Open Font License 1.1 |
| Site code | Astro (static site generator) | Building the pages | MIT |
Notes
- Works of the U.S. federal government are not protected by copyright (17 U.S.C. 105). Data from states and other bodies may have other rules; each row above names the license we read.
- We do not use agency logos, seals or insignia.
- Figures are unofficial copies for general information. Always check the official source.