Ninety Percent

Tomorrow evening, August 12, 2026, the Moon will do something it has not done in Luxembourg for a very long time. It will cross the face of the Sun and cover roughly 90% of it. A deep partial solar eclipse, visible across the entire Grand Duchy, beginning around 7:20 PM and reaching its peak near 8:15 PM [1].

The last time anything close to this happened here was August 11, 1999. That was a total solar eclipse across parts of Europe, and many people alive today still remember it. Schools stopped. Offices emptied. The sky went strange and the birds went quiet. For those who saw it, the memory stuck [2]. Tomorrow will not bring totality to Luxembourg, but it will be the deepest partial eclipse visible here since that day.

Here is what happens. The Moon passes between Earth and the Sun, casting its shadow. Because the Sun is about 400 times wider than the Moon but also about 400 times farther away, the two appear roughly the same size in our sky. When the alignment is right, the Moon can block the Sun entirely. Tomorrow, the path of totality crosses Greenland, Iceland, and northern Spain. Luxembourg sits outside that path, so we get the partial show [2].

And what a show. At peak, around 8:15 PM, the Sun will sit only about 6 degrees above the western horizon. That is low. Hills, buildings, trees, anything on your local skyline could hide it. You will need a clear western view. The Sun will be a thin crescent, 90% covered, hanging just above the horizon in the fading evening light [1].

The timing is remarkable for a second reason. August 12 is also the peak night of the Perseid meteor shower, and the eclipse happens during a New Moon. Dark sky, shooting stars, and a crescent Sun all in the same evening. The organizers of the Ettelbruck event at Hall du Deich planned for exactly this, with safe solar observation in the early evening followed by astronomy and Perseid watching after sunset [3].

Do not look at it

This part is serious. Even when 90% of the Sun is covered, the remaining 10% is bright enough to cause permanent retinal damage. There is no moment during tomorrow's eclipse when it is safe to look at the Sun without proper protection. Ordinary sunglasses, even very dark ones, are not enough. You need certified solar viewing glasses that meet the ISO 12312-2 standard [4].

Before using eclipse glasses, inspect them. If they are scratched, bent, or have pinholes, throw them away. When you look at the Sun, put the glasses on first, then turn toward it. When you are done, turn away first, then take them off. Every time, no exceptions [3].

Do not look through a camera, binoculars, or telescope while wearing eclipse glasses. Lenses focus sunlight and can burn through the filter, causing serious eye injury. Children need supervision. If you cannot find proper glasses, a pinhole projector is a safe alternative: punch a small hole in a card, hold it up, and watch the projected image on a surface behind it [4].

Where to go

The biggest public event is in Ettelbruck at Hall du Deich, organized by Nightwise with the Luxembourg Science Center and several partners. It is free, family-friendly, and runs from 5:00 PM into the evening. Safe solar observation, live broadcasts of the total eclipse from locations along the path of totality, family workshops, and after sunset, Perseid meteor watching under dark skies [3].

The Luxembourg Science Center in Differdange is also running eclipse programming over three days, August 11 through 13, with planetarium shows and safe solar observation activities [5].

If you cannot make it to either, find a spot with a clear western horizon. A hilltop, a rooftop, a field facing west. The eclipse starts at 7:20 PM, peaks at 8:15 PM, and the Sun will be very low. Cloud cover will determine everything. The current forecast for tomorrow in Luxembourg is sunny and bright, with temperatures around 30 degrees and a yellow heat warning for the south of the country [6].

Why eclipses matter

An eclipse is a reminder that the universe does things on a schedule we can predict centuries in advance but still struggle to comprehend in the moment. The Moon is 384'000 km away, moving at about 1 km per second, and it will line up with the Sun and the Earth to within a fraction of a degree, at exactly the time we said it would. That precision is worth pausing for.

Luxembourg will not see totality tomorrow. But 90% is enough to make the light strange, the shadows sharp, and the air feel different. The next total solar eclipse visible from Europe is in 2027. The next deep partial eclipse of this magnitude visible from Luxembourg is years away. Tomorrow is the one you get.

Go outside. Bring glasses. Look west.