The key to your solar viewer is the pin hole.
A solar eclipse is just around the corner! On 20 April this year, people around Australia and parts of Asia will have the opportunity to see the special event. Directly staring into the Sun is very dangerous, so learn how to safely watch the solar eclipse by building a solar eclipse viewer with us.
Safety: 
Never look directly at the Sun – it can cause eye damage and blindness. Protect yourself from the sun by wearing a hat, shirt, sunglasses and sunscreen. Be careful with scissors and always ask an adult for assistance if you’re unsure.
You will need
- Two pieces of cardstock or cardboard
- Scissors
- Tape
- Aluminium foil
- Ruler
- Pen or pencil
- Skewer or toothpick (anything small and pointy)
What to do
Using a ruler, draw out a 15-centimetre by 15-centimetre square on a piece of cardstock or cardboard.
Cut out the 15-centimetre by 15-centimetre square with a pair of scissors. If you find it hard to get started, ask an adult to help.
Cut out enough aluminium foil to completely cover your square shaped hole on the cardstock and tape it down.
Use something pointy, such as a toothpick, skewer or pin, to make a small hole in the centre of the foil.- Go outside and find an open area with full sun. Place your second piece of cardstock or cardboard on the ground.
- Stand with your back facing the Sun and hold your aluminium foil-covered cardstock above your head.
Move your cardstock around until you can see the sunshine through the hole in the foil make a circle on the second piece of cardboard.- Use this simple solar eclipse viewer to see any upcoming solar eclipses!
What’s happening?
There’s a good reason to not stare directly at the Sun: its energy is so strong it will give your eye a literal sunburn! By building a solar eclipse viewer, you’re creating a projected image of the Sun onto the cardstock on the ground. This is one of the safest ways to see solar eclipses. The cardstock on the ground works like a whiteboard under a classroom projector, allowing you to see the image of the Sun without looking directly into the Sun.
The key to your solar viewer is the pin hole. The image of the Sun you see is made entirely from light that passed through that hole. But the light from the top of the Sun had to come at a very specific angle to get through the hole. And light from the bottom of the Sun had to come from a slightly different angle. You can imagine a cone of light starting from all across the Sun, and coming to a point exactly at your pinhole!
Past the pinhole, the light spreads out into another cone. This one’s back-to-front and upside down compared to the real Sun. But it will still have details like big sunspots and any Moons that happen to be getting in the way.
It can take some fiddling to get the very best image. Lifting the pinhole away from the ground will make the image larger but less bright. Making the pinhole bigger will make the image brighter, but less focused. You can try angling the bottom sheet of cardboard to make the Sun more circular rather than an oval too!
What is a solar eclipse?
A solar eclipse is when the Moon happens to pass between the Sun and the Earth. Sometimes the Moon only blocks part of the Sun, and this is called a partial solar eclipse. When the Moon blocks all of the Sun, this is a total solar eclipse. There are also annular eclipses, which happen when the Moon is further away from Earth than usual. In this case, the Moon can be directly in front of the Sun and not block it all. A small ring of Sun, called an annulus, can be seen around the Moon!
If you’re looking for more eclipse information, why not pick up a copy of Eclipse Chasers, by Nick Lomb and Toner Stevenson? It’s a fantastic guide to past and future Australian total solar eclipses, exploring historical and cultural knowledge, as well as featuring five upcoming eclipses that will be visible in Australia.
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