Follow the Solar Eclipse of March 29, 2025
A partial solar eclipse will take place on Saturday, 29 March 2025 and will be visible in Belgium. Instruments of the Royal Observatory of Belgium will observe it. If the weather permits it, there will also be an observation event at the Planetarium.
In Uccle, the eclipse will be visible between 11:14 (first contact) and 13:01 (last contact), and its maximum will take place at 12:07 Belgian time (UTC + 1 h). From Belgium, this will be a small eclipse, with the moon only covering about 35% of the solar diameter during the maximum. This corresponds to about one fifth of the solar surface. Hence, this event will not cause a noticeable darkness in the middle of the day.
For the visibility of the eclipse in other regions of Belgium, you can consult our web page: https://robinfo.oma.be/en/astro-info/eclipses/eclipses-2025-en/#eclipse-29-march-2025
How to observe the eclipse
A pair of eclipse glasses
Caution: never look directly into the Sun. Looking at the Sun can irrevocably damage the retina. Sunglasses are not sufficient to protect your eyes. Instead, use special eclipse glasses to observe, such as the ones shown in the picture on the left. Eclipses glasses are sold at the Planetarium of Brussels for 2.5 € per piece.
If you do not have eclipse glasses, you can observe the solar eclipse through projection with two cardboards: make a small hole in one of the cardboards using a pin or a thumbtack and make sure the hole is round and smooth. Without looking directly at the Sun, let the sunlight shine on this holed cardboard. The second cardboard will act as a screen (you can also use a wall or the ground as an alternative). Hold the cardboard at a distance (minimum 1 m) from your screen, and you will see an inverted image of the Sun projected through the pinhole.
Schematics of a projection box used for observing the Sun. Credit: Curtis Newton (Wikimedia (CC-BY-SA 2.0), modified by L.B.S. Pham).
If you use binoculars or a telescope for observing solar eclipses, only do it with the projection technique described above (with the telescope or binocular replacing the pierced cardboard), unless you use them with solar filters specifically designed for solar observation.
The Planetarium and the Observatory observe the eclipse
If weather permits, the Planetarium of Brussels will organise an observation event with a solar telescope in its parking lot. Moreover, several instruments managed by the Royal Observatory of Belgium will follow the 29 March 2025 solar eclipse up close.
If weather permits, too, images of the solar telescopes at Uccle will be broadcast live via this link: https://www.sidc.be/uset/Eclipse2025/. The live images will be made in different wavelengths: in White light, showing the familiar solar disk with sunspots, in the red spectral line of hydrogen (H-alpha) and in the calcium line (CaII-K), which lies in the blue part of the visible spectrum. Both H-alpha and CaII images show a higher layer of the solar atmosphere, called the chromosphere, and reveal prominences and plages, respectively.
The solar eclipse will also be observed in space, with the SWAP telescope and LYRA radiometer onboard the PROBA2 satellite: https://proba2.sidc.be/NearlyTotalEclipse. Those instruments will observe this eclipse from a perspective where the Moon will cover 99% of the Sun. Images of the eclipse will be taken in extreme ultraviolet, showing solar flares and active regions on the solar surface, and will be published some time after they will be taken.
The previous solar eclipse visible in Belgium took place on 25 October 2022. USET and PROBA2 took images of this event as well.
Picture of the partial solar eclipse of 25 October 2022 taken by the solar telescope onboard USET in visual light. Credits: USET/ORB-KSB.
Solar eclipses usually occur two to three times a year. The next solar eclipse visible in Belgium will take place next year, in the early evening of August 12, 2026 and with a maximal occultation of 90 % of the solar surface. Be aware that this event occurs at sundown, so you will need a clear view of the horizon to look at the eclipse. The Royal Observatory is already looking forward to observing this almost total solar eclipse!