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Don’t forget the solar eclipse on Friday

On Friday 20 March, Denmark will experience a partial solar eclipse. Make sure you look up safely to avoid damage from UV rays.

A solar eclipse occurs when the moon moves in front of the sun. This darkens an area on Earth for a few minutes, and allows the corona, the sun’s outer gas layers, to be seen as a flare around the sun disc.

While it is an interesting and beautiful phenomenon, the scientific output of a solar eclipse is relatively limited:

“We don’t really research eclipses anymore, it is a bit of an outdated field,” says Klaus Galsgaard, Associate Professor at Astrophysics and Planetary Science, Niels Bohr Institute, UCPH.

“What we can do, is use the darkening of the sun to gain a better understanding of the solar corona. Normally, the white light emitted by the sun blots out everything else, but when an eclipse occurs, it allows us to perform spectroscopic observations (the identification of matter via its interaction with light, ed.) without the very strong light from the sun.”

That doesn’t mean astronomers sit around waiting for eclipses to happen. Nowadays, satellites create artificial eclipses, allowing physicists to gather their data without having to depend on clear skies.

Beware the UVs

It is important to never look directly at a solar eclipse, even when the sun is darkened. This is because harmful UV rays can damage your eyes.

Ordinarily, looking at the normal sun is impossible for more than a few seconds, which ensures that your eyes are not harmed too much by the UV radiation emitted by the sun.

But it’s physically possible for your eyes to look at a darkened sun during a solar eclipse for much longer. Unfortunately, you are still exposed to the full brunt of UV rays, increasing the risk of eye injury.

While sunglasses, photographic film and stained glass can go some way to filtering out UV rays, they are not recommended substitutes. UV rays can fry your retina and cause permanent eye damage.

How to safely view an eclipse

In order to view the darkening of the sun safely, you can punch a hole in a piece of paper, let the sun shine through and onto a white surface, and then view the shadow of the solar eclipse.

Another good way to indirectly view solar events is to set up a telescope or a pair of binoculars with a white surface behind it for the sunbeam to shine onto.

This allows for safe observation of the sun’s surface, without the interference of rays. However even with this technique you should avoid looking directly at the sun.

Only proper eclipse sunfilter glasses, such as these, can be used to look directly at the sun.

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