C1 · High Atlas, Morocco · Landfall
Totality
On 2 August 2027 the Moon's shadow makes landfall on the Moroccan coast and runs east across North Africa. Near the Nile it is still moving at roughly 2,400 kilometres an hour.
Southeast of Luxor it will stand over the desert for six minutes and twenty-three seconds. No total eclipse over land will last longer for the rest of this century.
The coincidence
Four hundred
and four hundred.
The Sun is about four hundred times wider than the Moon. It is also about four hundred times further away. The two discs therefore appear almost exactly the same size from the ground.
Nothing requires this. It is a coincidence of our particular moment, and it is the only reason a total eclipse looks like anything at all.
C1 → C2 · 78 minutes
Nothing appears
to happen.
For more than an hour the Moon eats the Sun and almost nobody notices. The eye adapts faster than the light falls. At half covered the day looks ordinary. At ninety per cent it looks like a passing cloud.
Human vision is logarithmic. It is built to see across eleven orders of magnitude, which makes it superb at seeing and useless at measuring.
Pinhole projection
Every gap
becomes a lens.
Any small aperture projects an image of its light source. Under a tree the overlapping leaves make thousands of them, and the dapples on the ground stop being round.
They become crescents, all leaning the same way, tracking the geometry overhead. It is the first moment the eclipse becomes undeniable at ground level.
T minus 30 seconds
Shadow bands.
Faint grey ripples race across pale ground in the last seconds before totality. They are low contrast, fast, and notoriously hard to photograph.
They are generally attributed to atmospheric turbulence scintillating the thin remaining crescent, in the same way stars twinkle. The full explanation is still not settled.
C2 · Second contact
Baily's beads,
then the ring.
The Moon's edge is not smooth. In the last instant, sunlight streams through its valleys and the vanishing crescent breaks into separate points of light.
One bead outlives the others. For about a second it sits on a ring of pearl-coloured light, and then it goes out.
Totality · 06m 23s
The corona.
The Sun's surface is about 5,772 kelvin. The atmosphere above it, invisible on every other day of your life, is one to three million.
Heat is not supposed to flow from the cooler thing to the hotter thing. Why the corona is hundreds of times hotter than the surface beneath it is an open problem in physics.
The umbra
You are standing
inside a cone.
The shadow is not overhead. It is around you, a cone of darkness roughly 258 kilometres wide, and you are inside it.
Look at the horizon in any direction and you see daylight, because out there the eclipse is only partial. A sunset in every direction at once.
C3 · Third contact
And then
it is over.
The diamond ring runs backwards. The corona is gone in less than a second, not because it left but because it was never bright enough to compete.
It is there right now, above your head, drowned out.
Greatest eclipse · 25°30′N 33°11′E
Luxor,
six minutes
and twenty three.
The Nile, west bankPoint of greatest eclipse
Closing
A temporary
arrangement.
The Moon is moving away from us at about 3.8 centimetres a year, roughly the rate your fingernails grow.
Eventually its disc will be too small to cover the Sun, and there will never be another total eclipse. Every one that remains is happening inside a window that is closing.
We are alive during the part where it still works.