Helios and a Partial Solar Eclipse

Heather Jackson, 31 Gorffennaf 2026

On Wednesday 12^th August 2026, people in Wales will be able to see a partial solar eclipse. This is where around 90% of the Sun will be covered by the Moon.

This will be the closest to a total eclipse the UK has seen since 1999, and you'll have to wait until 2090 for the next total solar eclipse visible from Wales!

At the same time, visitors to Amgueddfa Cymru: National Museum Cardiff will have the chance to explore Helios, a spectacular illuminated installation by artist Luke Jerram. Visitors will be able to experience both the Sun in partial eclipse and explore an up-close artistic interpretation.

National Museum Cardiff will be opening late on the 12^th August to celebrate the eclipse. To help you view it safely, we will be making eclipse viewers in the Clore Discovery Centre throughout the day out of cereal boxes. Why not bring along a cereal box and turn it into your own scientific instrument? Tickets to this event are free and can be booked from our website - Museum Lates: Solar Eclipse.

What is a solar eclipse?

A solar eclipse occurs when the Earth, Moon and Sun align. The Moon passes in front of the Sun and blocks its light, casting a small shadow on Earth. As the shadow is quite small compared to the size of the Earth, only a few countries see the eclipse.

Map o Eclips Cyflawn yr Haul, 12 Awst 2026

On the 12 August, the path of totality falls over Greenland, Iceland and Spain. People in the UK, France, Belgium, Switzerland and northern Italy will see a partial eclipse, where a portion of the Sun (90%) is covered by the Moon.

For Wales, it will be as close to a total eclipse as we’ve seen in 27 years!

Historical eclipses in Wales

Total solar eclipses are very rare in Wales but there are records of them. The last one was in June 1927, but the weather was bad with dark clouds and heavy rain.

For the eclipse of 1836, Wales fared better. The following poetic report appeared in Y Seren Ogleddol (The Western Star) afterwards. The original inhabitants of the Rhyd y Car cottages and Cilewent Farmhouse at St Fagans National Museum of History would have witnessed this eclipse in much the same way as this writer.

DIFFYG AR YR HAUL
Cymerodd y peth anarferol hwn le, Sabbath y 15 o Fai, yn union yn yr amser. Mewn rhai mannau yn y dywysogaeth, dywedir bod y brain yn mynd i'w coedwigoedd, yr adar yn mynd i'w nythod, a'r ystlum yn dangos ei hun; yr ieir yn chwilio am eu clwydau. Yr oedd natur wedi llawn prydferthwch, felpetai wedi ei daro â syndod a rhyfeddod; yr awyr yn oer a thywyll, fel pe bai rhywbeth annormal yn dod i'r ddaear; ac wedi i'r gwanwyn godi, dyma natur yn codi o farwolaeth i fyw, yr ystlumod yn dianc i'w tyllau, a'r adarbach yn canu'n hapus i'w Creawdwr, a phob peth yn edrych mor brydferth a dymunol a cynharach.

SOLAR ECLIPSE
This unusual event took place on Sabbath, 15th May, exactly at that time. In some parts of the county, it is said that the crows went to their woods, the birds went to their nests, and the bats appeared; the hens went to roost. Nature that was full of beauty, appeared as if struck with wonder and amazement; the air was cold and dark, as if something abnormal was coming to the earth; and after the sun reappeared, nature arose from death to life, the bats escaped to their holes, and the little birds sang happily to their Creator, and everything looked as beautiful and pleasant as before.

What will happen on 12^th August 2026?

6.17pm (Cardiff): The Moon will first cover part of the disk of the Sun.

The Moon will move slowly in front of the Sun until roughly 90% of the Sun is covered.

7.12pm (Cardiff): The eclipse maximum, where enough of the Sun will be covered to make a noticeable difference in the temperature and light levels. The sky will not actually become dark.

After the maximum, the Moon will slowly move off the Sun’s disk until only a small sliver remains.

8.06pm (Cardiff): the eclipse ends.

As this will happen as the Sun is setting, the Sun and Moon will become increasingly low on the horizon as the eclipse goes on. The best way to see the eclipse will be from a high point with a clear view of the western horizon. We can only cross our fingers for cloudless skies!

Your view will also depend on where you are in Wales – Pembrokeshire will have the best views. There 94% of the Sun will be covered by the Moon.

If you’re planning to view the eclipse on the 12^th August, why not visit Helios for a close-up view of the Sun beforehand to discover what the Sun looks like up close?

Llun cyfansawdd o eclipse rhannol yr haul o Ganolfan Ofod Johnson NASA yn Houston, 21 Awst 2017

How to view a solar eclipse

You should never look directly at the Sun, even during an eclipse. Doing so can severely damage your eyes.

We will be making eclipse viewers throughout the day on the 12^th August so why not come along to make your own.

You can safely watch the 12th August partial solar eclipse using:

1. Eclipse glasses – Special eclipse glasses can block out the Sun’s harmful rays and enable you to look at the eclipse safely. Normal sunglasses are not safe to use! Make sure your eclipse glasses have safety certification ‘ISO 12312-2' printed on them. Don’t reuse any old eclipse glasses: they may not be safe. Even a microscopic scratch in the lenses could damage your eyesight.

2. A solar telescope – Check with your local astronomical society to see if they’re running any eclipse-viewing events on 12 August. They may have a few telescopes fitted with special solar filters, which are safe to use to observe the Sun. you should never use normal telescopes or binoculars to look at the Sun.

3. Make a pinhole projector – There are a few ways you can make a ‘pinhole projector’, which will allow you to see the eclipse by projecting the Sun’s light, and the bite being taken out of it, onto another surface. Try this one: Make your own pinhole camera | The Schools' Observatory. You can even use a kitchen colander to project an image of the eclipse safely on the ground!