SAFE VIEWING of the SUN Total Eclipse in USA 21 August 2017Using a mirror as a pinhole to produce an image of the sun perfect for SOLAR ECLIPSES or TRANSITS of VENUSAny Solar Eclipse (total, partial, annular) can be viewed easily and cheaply by a reflected pinhole. The same method is used for viewing the Transit of Venus and for viewing sunspots - or even just for looking at the sun.
|
This technique was used to observe the Transit of Venus in Trinity College Cambridge on 3 June 2004. The advantage is that a large number of people can watch at the same time. Several other methods for viewing the Transit were available, but the simplest and safest was the "reflected pinhole", described below. It was also used to observe the Partial Eclipse on 3 October 2005.
Eye Safety - do not look at the sun directlyThe simplest and safest method to produce a clear image of the Transit is to use a 'reflected pinhole' which is just a small mirror, as shown here, blacked out with tape leaving a small square, say 5mm x 5mm (1/4" x 1/4") (the smaller the square the sharper the image, but it will be less bright). If you reflect the sunlight through the window onto the wall of a darkened room then you get a perfect circle which is the disc of the sun. The mirror needs to be about 30 metres (30 yards) away from the wall to get a sharp image. You should use a smaller square (pinhole) if you want a shorter distance. Use some putty or plasticene to fix the mirror to a table, chair, wall or post - the mirror needs to be held still to prevent the image from wobbling.The method has many advantages: Now all you have to hope for is a sunny day ...
| A mirror, taped over to leave a 5mm x 5mm square
| Image reflected into darkened room |
Jonathan Hunt, aged 1 |
Ricardo the cat, aged 13 |
Ricardo |
a good image of venus |
Sandy Hunt aged 7, on his birthday |
hemh1 (at) cam.ac.uk |