Where these numbers come from
This is an independent guide to the total solar eclipse of Monday 2 August 2027. Every duration, contact time, obscuration, magnitude and Sun altitude on the site is computed from the JPL DE440 ephemeris by our own code, not copied from anywhere, and not rounded off into vagueness.
What this site is
On 2 August 2027 the Moon’s shadow crosses Egypt at midday and delivers up to 6 minutes 23 seconds of totality, the longest visible from land anywhere on Earth between 1991 and 2114. This site exists to answer the practical questions that follow from that: where the path actually runs, how long totality lasts in each town, what time it happens on your watch, how high the Sun will be, what the weather usually does in early August, and how to watch it without hurting your eyes.
It is written and maintained by one person as an informational project. There is no organisation behind it, no sponsor, and nothing for sale. Where a fact can be computed, it is computed. Where something is genuinely uncertain (which temple forecourts will be ticketed, what a hotel room will cost in 2027), the site says so rather than inventing a number.
How the eclipse numbers are produced
Every eclipse figure on this site (the contact times, the duration of totality, the percentage of the Sun covered, the eclipse magnitude, the Sun’s altitude and azimuth) comes from a single calculation, run for the exact coordinates of each place.
The source data: JPL DE440
The input is the JPL DE440 ephemeris from NASA’s Jet Propulsion Laboratory: the positions of the Sun and the Moon to a precision far beyond anything an eclipse watcher needs. For each place we take the apparent Sun and Moon as seen from that exact point on the WGS-84 Earth, and solve for the four contacts, the moment of maximum eclipse, the Sun’s altitude and azimuth, and the share of the Sun that is covered. Our Spanish sister site uses exactly the same dataset.
| Eclipse | Total, 2027 August 02 |
|---|---|
| Ephemeris | JPL DE440 (de440s) |
| Software | Skyfield (Python) |
| Lunar radius | k = 0.2722810 |
| ΔT (TT − UT) | 69.1 s |
| Earth model | WGS-84 ellipsoid, sea level |
| Path geometry | Our own DE440 path, central line and limits |
One detail worth flagging, because it is where eclipse predictions differ: the Moon moves on a uniform time scale, but clocks follow the Earth’s slightly irregular rotation. The difference is ΔT. We use 69.1 seconds, in line with current IERS measurements. NASA’s 2027 pages were prepared years ago with 71.7 seconds, so NASA’s clock times run four to five seconds earlier than ours, and near the path edges its durations can differ by several seconds.
The map
The central line and the northern and southern limits on the interactive map come from the same DE440 calculation, smoothed between points with a centripetal Catmull-Rom spline. Click a town marker and you see the numbers of its page. Click anywhere else and your browser computes that spot with NASA’s Besselian elements, using our ΔT. That agrees with the town pages to about a second, and to three or four seconds within a few kilometres of an edge.
How accurate is it, and how would you check?
- Run on the total eclipses of 2017 and 2024, the same code reproduces NASA’s published greatest durations to within 0.3 seconds.
- For 2027 it agrees with Xavier Jubier’s calculator to about half a second in duration and one second in contact times, at 13 places from Spain to Saudi Arabia.
You can check any number yourself with the NASA map (allow for its older ΔT) or with Jubier’s map.
The honest limits of the calculation
The Moon is treated as a smooth sphere. Real contact times are shifted a second or two by lunar mountains and valleys, and by up to six or seven seconds close to the path edge. If you are chasing the last few seconds of totality near a limit, use a limb-profile prediction such as Jubier’s. Times are also computed at sea level for each town’s listed coordinates; move ten kilometres and the seconds move too. That is exactly what the map is for.
Conventions used throughout
- All Egyptian local times are EEST, UTC+3. 2 August 2027 is a Monday. Locations outside Egypt use their own local time, marked as such.
- In the timelines, first and last contact (C1, C4) are given to the minute; the start, middle and end of totality (C2, maximum, C3) are given to the second, because there the seconds matter. The “in numbers” table on each town page gives every contact to the second.
- Obscuration is the fraction of the Sun’s disc area covered. Magnitude is the fraction of its diameter covered. The two are not the same number, and the difference is why 99% sounds close to totality and is not.
What this site does not do
It is worth being blunt about this, because plenty of eclipse pages exist to sell you something.
- It is not a booking service. You cannot book a room, a tour, a boat or a flight here, and there is nothing to buy.
- There is no commercial relationship with any tour operator, hotel, cruise line or eclipse-glasses vendor: no affiliate links, no paid placements, no sponsored recommendations. When a page says a place is good, that is a judgement about geometry, climate and logistics, not a transaction. If that ever changes, the affiliate disclosure will say so first.
- It does not give travel, visa, security or health advice. Those come from your own government and from the Egyptian authorities, and they change. See Plan your trip for what the site can usefully say, and the disclaimer for what it cannot.
- It does not forecast the weather. The weather pages describe long-run August climatology. A forecast for 2 August 2027 will not exist until a few days beforehand.
- It will not tell you an unfiltered look is fine. See eye safety; use ISO 12312-2 certified filters.
Corrections welcome
If you find an error (a contact time that disagrees with your own calculation, a place described wrongly, a broken link, a claim that has quietly stopped being true), please say so. Astronomical corrections are especially welcome, and if you can show the working, better still. Get in touch; the page will be fixed and, where the change matters, noted.