What to expect, and how to plan

People who have seen totality are unanimous and slightly tedious about it: it is not a bigger version of a partial eclipse, it is a different event. Here is what actually happens, in order, and what to do about it.

The hour before

First contact is undramatic. Through your filter a small notch appears on the Sun's edge, and for the next forty minutes very little seems to change. Your eye adapts to a falling light level almost perfectly, so even at 80 percent coverage the afternoon looks normal — perhaps oddly crisp, because the Sun has become a narrow crescent and is casting sharper shadows than usual.

This is the phase people underestimate. Look at the ground under a leafy tree: every gap between leaves is a pinhole camera, and the dappled light turns into hundreds of crescents. It is one of the best parts of the whole thing and it is free.

The last five minutes

Now it moves quickly. The light goes strange — thin, silvery, with an unfamiliar colour cast that photographs never capture. The temperature drops noticeably. Birds settle. The western sky darkens in a way that does not look like sunset because it is happening in the wrong part of the sky and far too fast.

In the last minute, if the ground is pale and the air steady, you may see shadow bands — faint ripples of light and dark racing across the ground, a few centimetres apart. They are an atmospheric effect and are notoriously hard to see; a white sheet laid out helps.

Totality

Second contact: the last of the photosphere breaks into Baily's beads as sunlight shines through valleys on the Moon's edge, then collapses to a single brilliant point — the diamond ring — and goes out.

Then the corona. It is not white in the way a photograph suggests but pearly and structured, with streamers reaching out a solar diameter or more, and it is startlingly sharp-edged against a sky the colour of deep twilight. Around the Moon's rim, pink flecks: prominences, loops of hydrogen bigger than the Earth. Venus will be obvious high to the left of the Sun; Jupiter and Mercury sit close in, and Regulus is only about nine degrees away.

From northern Spain there is a further oddity. Because the Sun is so low, you are looking at the corona through a great thickness of atmosphere and against a sky already coloured by sunset, and the whole horizon behind you glows orange — the light from outside the shadow, a couple of hundred kilometres away in every direction.

Then it ends, without ceremony. Totality lasts 1m 42s at Palencia and only 59s at Valencia. Filters back on the instant the first bead of light returns.

Planning, honestly

Be inside the path

Not near it. There is no partial credit. Check your exact spot in the simulator and give yourself several kilometres of margin from the limits.

Stay mobile

The single most useful thing you can do is be willing to move on the morning. Book somewhere central to the path with roads in several directions rather than committing to one viewpoint.

Check the western horizon

For Spain this matters as much as the sky overhead. Visit your site in advance, in daylight, and look towards where the Sun will be — around west-north-west.

Expect crowds and traffic

Northern Spain in mid-August is already busy. Arrive early, bring water, and assume roads afterwards will be slow — everybody leaves at the same minute.

Set your watch

Know your second and third contact times to the second and set an alarm a minute before. People routinely miss the diamond ring because they were looking at a screen.

Have a cloud plan

Decide in advance what forecast would make you drive, and how far. Under thin cloud you will still get the darkness; under thick cloud you get nothing but the dark.

Photography, briefly

The honest advice for a first total eclipse is: do not. You get one attempt at something that lasts a minute, and pictures of this eclipse will be everywhere within the hour. If you do shoot:

A front-mounted solar filter is mandatory for the partial phases and must come off for totality — practise the swap until it takes two seconds.
Because the Sun is low, a wide shot with landscape is far more interesting than a tight one, and much easier. A 24–70 mm lens on a tripod will give you something no high-Sun eclipse can.
For a close-up of the corona you need roughly 400 mm or more, and a bracket of exposures from about 1/1000 s to 1 second at f/8, ISO 400 — the corona's brightness range is enormous.
Turn off autofocus, autoexposure and any flash. Focus manually on the Moon's edge beforehand.
Set the camera running on an intervalometer and then look up with your own eyes.

Common questions

Why is this called the first total eclipse over mainland Europe since 1999?

There have been total eclipses visible from European territory since — notably 20 March 2015 over the Faroe Islands and Svalbard — but none whose path of totality crossed the European mainland. The last one to do that was 11 August 1999, which ran across Cornwall, northern France, Germany, Austria, Hungary and Romania.

Will it go completely dark?

Not quite. Totality is about as dark as deep twilight — you can still see your hands, read a watch face with difficulty, and the horizon glows in every direction because the shadow is only a few hundred kilometres wide. It is dark enough for the brighter planets and stars.

Why does the Moon appear to move across the Sun from one side to the other?

The Moon travels eastward against the background sky, roughly its own diameter every hour, so it always covers the Sun from west to east. Which way that looks to you — bottom-right first, or top-left — depends on how the horizon is tilted relative to the sky where you are, which is why the simulator rotates the geometry to match your latitude and the time of day.

Is a 99 percent partial eclipse nearly as good?

No, and this surprises people every time. The Sun's surface is so bright that one percent of it still outshines the corona by a factor of thousands. At 99 percent the sky is still blue, the corona is invisible, and you cannot take your filter off. Totality is a threshold, not a gradient.

How accurate are the times on this site?

The contact times come from NASA's own Besselian elements for this eclipse and agree with published predictions to within a few seconds. The main uncertainty is not the arithmetic but the Moon's ragged edge: near the northern and southern limits, mountains on the lunar limb shift the true boundary by a kilometre or two, which is why the simulator warns you when you are that close to an edge.

What if it is cloudy?

You still get the darkness, the temperature drop and the eeriness, which is more than nothing. But the corona is the point, so if the forecast is poor and you can move, move. Inland Castile and the Ebro valley are much drier than the Cantabrian coast.

If you miss it

Spain is unusually lucky over the next few years.

2 August 2027 Spain (Cádiz, Málaga), Morocco, Algeria, Libya, Egypt, Saudi Arabia
The long one: up to 6m23s of totality near Luxor, with the Sun almost overhead. Southern Spain catches nearly three minutes.
26 January 2028 Spain (annular), Portugal, Caribbean, Brazil
An annular eclipse — the Moon is too far away to cover the Sun, leaving a ring of light. Never safe to look at without a filter at any moment.
12 August 2045 United States, Caribbean, South America
The next great American eclipse, with over six minutes of totality.