A total solar eclipse is set to sweep over America. But making sure that everyone there can enjoy it is important work.

It is one of the most stunning sights that can ever be seen in the sky, and the opportunity to do so only emerges rarely. The whole of North America will get that chance on 21 August, when a total solar eclipse will make its way across the continent, turning day into night.

The central problem with the eclipse is that the star of the show is the sun. Even though it will be sliding behind the moon and out of proper view, all the normal caution must apply, since looking straight at it can cause such damage.

As such, Nasa says that anyone looking to observe the eclipse must not do so directly. Instead, you can either use eclipse glasses, which work like very intense sunglasses, or an indirect method.

To use them, stand still and put on your sunglasses while not looking up at the sun, and then look towards it. Make sure to do the same when you remove them.

The only time it's safe to look right at the eclipse is when it reaches totality, and the sun passes behind the moon and turns day into night. That will last for about two minutes and 40 seconds, after which you'll need to put them back on.

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