How to watch the eclipse on the side of your car

There will be a solar eclipse visible in the UK on Friday (20 March), peaking at around 09:30-09:45 in the morning, depending on where you are.  This BBC News article describes when and where it will be visible.  It also links to the Royal Astronomical Society webpage, which has a How to Observe an Eclipse Safely guide.  The secret is not to look at the Sun.

This post describes a method that is a cross between the RSA’s pinhole and binocular methods.  We used it to watch an eclipse when we were doing geological fieldwork Tenerife in September 2005.

Project the eclipse onto the side of your car

You will need

1. A piece of card or paper (to create a shadow)
2. Binoculars (to magnify and focus the image)
3. A car, or similar smooth surface (to project the image onto)

Rodrigo del Potro projecting an eclipse onto a car. Make the image larger by moving the binoculars further from the car.

Using the paper casts a shadow on the car that makes the image from the binoculars much easier to see.

Instructions

1. Make a hole in the middle of the card about the size of the eyepiece lens on the binoculars.
2. Put the card against the binoculars so that one of the eyepieces is over the hole.
3. Hold both in front of the car so that the paper casts a shadow.
4. While looking at the car, angle the binoculars towards the Sun.

The final stage is the tricky one, as the Sun is a small target and it’s hard to know exactly where the binoculars are pointing.  The shadow cast by the binoculars onto the sunny side of the paper can help you to position them – try to make it as small as possible.  You can sharpen the image using the focus control on the binoculars.

Improvements

There are obvious ways in which to improve this, such as putting the binoculars on a tripod and using tape to attach them to the card.  The appeal of this method is that it is quick, and it only needed things that we already had with us.

Warning

This should be totally obvious, but I’ll say it anyway:

DO NOT LOOK DIRECTLY AT THE SUN THROUGH BINOCULARS!!!

If you want to know why, just try holding your finger where your eye would be.

The forecast is for clouds in Edinburgh on Friday morning, but maybe we’ll get lucky and there will be a break so we can see it.  Enjoy!