Data sources & licences
This site is built entirely on open data and open-source software. Thank you to everyone who collected, shared and maintains it. Here is exactly what we use and the licence each part comes with.
- Data version
- Facts generated 2026-10-12
- Last refreshed
- 2026-10-12
EclipseWise (Fred Espenak)
Credit: Eclipse Predictions by Fred Espenak (EclipseWise.com), from the page for the total solar eclipse of 2027 August 2
Used for: The Besselian elements behind every time, duration and path on the site, and the city tables we check our calculations against.
Licence: Free to use with credit and a link to the eclipse page
Source: https://eclipsewise.com/solar/SEprime/2001-2100/SE2027Aug02Tprime.html
Version: Elements retrieved 12 October 2026
NASA/GSFC (Fred Espenak)
Credit: Eclipse map/figure/table/predictions courtesy of Fred Espenak, NASA/Goddard Space Flight Center, from eclipse.gsfc.nasa.gov.
Used for: NASA’s own element set and central-line path table, used to check the path.
Licence: NASA content, not under copyright unless marked
Source: https://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2027Aug02Tgoogle.html
Version: Retrieved 12 October 2026
GeoNames
Credit: GeoNames, CC BY 4.0
Used for: City names, positions, elevations and populations for search and the city pages.
Licence: CC BY 4.0
Source: https://www.geonames.org/
timezone-boundary-builder
Credit: Time zone boundaries © timezone-boundary-builder contributors, ODbL
Used for: Finding the local time zone of any point you tap.
Licence: ODbL
Source: https://github.com/evansiroky/timezone-boundary-builder
OpenStreetMap
Credit: © OpenStreetMap contributors, basemap by Protomaps, ODbL
Used for: The basemap.
Licence: ODbL
Source: https://protomaps.com/
Software
The map is drawn with MapLibre GL JS and PMTiles, and the site is built with Astro. These are open-source projects under their own licences.
Using our images and embeds
Images you download from the map and the embed code both carry the credits above. Please leave them in place.
Acknowledgement and eclipse page
All eclipse predictions on this site are based on the work of Fred Espenak. Eclipse Predictions by Fred Espenak (EclipseWise.com). The page for this eclipse is Total Solar Eclipse of 2027 Aug 02 on EclipseWise. NASA credit line: "Eclipse map/figure/table/predictions courtesy of Fred Espenak, NASA/Goddard Space Flight Center, from eclipse.gsfc.nasa.gov."
Delta T
The rotation of the Earth is slightly irregular, and the difference between uniform time and Earth-rotation time (Delta T) for August 2027 has to be forecast. The published tables assume 72.8 seconds (EclipseWise) and 71.7 seconds (NASA). We use 69.2 seconds, which is the recent measured value (checked 2026-10-12), so our times are about 3 to 4 seconds later than EclipseWise's. We will re-check it in spring 2027.
Safety information
The eye safety page summarises guidance from NASA and the American Astronomical Society.