Eclipse engine
Official polynomial Besselian elements by Fred Espenak,
on JPL DE405 ephemerides; mini-map paths from
EclipseWise (F. Espenak).
ΔT values from the IERS.
Ephemerides and sky
Astronomy Engine v2.1.19
(Don Cross, MIT license). Lunar libration for the orientation of Baily's beads.
NASA catalogues
NASA / GSFC Eclipse Web Site:
Five Millennium Canon & Catalog of Solar Eclipses, decade tables and the SEcat5 catalogue;
JavaScript Solar Eclipse Explorer (JSEX) for local circumstances. Saros–Inex series
anchored to NASA values.
Lunar topography — Baily's beads and contacts
Lunar limb profile from NASA LRO / LOLA data.
C2 and C3 are computed against the true limb, not a spherical Moon:
totality begins when the last Baily's bead is extinguished behind the real profile.
The difference from the mean limb reaches a few seconds.
Uncertainty ±0.6 s near the centre line, measured on 20 points of two eclipses against
Xavier Jubier's calculations.
It grows away from the centre of the path, where the limb relief weighs more on the contact:
towards the limits our figure and Jubier's can differ by a few seconds on the duration of totality.
The discrepancy concerns the limb models, not the eclipse circumstances: C1, C4, maximum and magnitude
agree with Jubier to within a tenth of a second everywhere.
C1 and C4 stay on the mean limb: they are penumbral contacts and the relief does not shift them measurably.
Solar corona
For the 12 August 2026 eclipse the corona is not a photograph but a
prediction: the white-light (K-corona) rendering of the magnetohydrodynamic
MAS model by Predictive Science Inc.,
driven by HMI/SDO vector magnetograms assimilated in near real time into the
HipFT flux-transport model
(Downs et al., A near-real-time data-assimilative model of the solar corona,
Science 388, 6753 (2025)).
Research funded by NASA and NSF. The image is used with attribution; the simulator rotates it to
match the orientation of the solar axis as seen from the observing site and applies the atmospheric
extinction corresponding to the Sun's altitude.
For every other eclipse the corona is a real photograph of the 21 August 2017
totality: the overall appearance is authentic, but the fine structure belongs to that date, not to
the simulated one.
Elevation — real horizon
Real horizon profile (Sun rise, culmination and set relative to the terrain) from
Terrain Tiles
(Tilezen/Mapzen, AWS Open Data, Terrarium format): SRTM and GMTED2010 data
courtesy of the U.S. Geological Survey; global ETOPO1 relief © NOAA.
For viewpoints in Italy the near field uses the 10 m
TINITALY/1.1 model
(CC BY 4.0):
Tarquini S., Isola I., Favalli M., Battistini A., Dotta G. (2023), TINITALY, a digital elevation
model of Italy with a 10 meters cell size (Version 1.1), Istituto Nazionale di Geofisica e
Vulcanologia (INGV), doi:10.13127/tinitaly/1.1.
For viewpoints in Spain (mainland, Balearics and Canaries) the near field uses the
5 m MDT05
model, derived from PNOA LiDAR, © Instituto Geográfico Nacional de España
(CC BY 4.0),
served over INSPIRE WCS by IDEE.
Summit elevations (natural=peak) from
OpenStreetMap
contributors (ODbL), queried through the
Overpass API.
An outreach project. NASA data and the cited authors' works are used for educational
purposes with attribution to the originals; not intended for navigation or precision scientific use.
Trademarks, catalogues and data belong to their respective owners.