ESA's Simon Dinwiddy has devised a way of viewing the Sun which is both safe and effective.
- Take the lens from a pair of +1 dioptre low-power reading glasses (available from most department stores).
This lens has a focal length of 1000 millimetres (1 metre).
- Take a small piece of wood (10 cm x 6 cm x 1 cm approx.)
and drill in the centre a hole of 10 mm diameter.
- Fix the lens over the hole.
- Fix the board to a long lath or rod (1 metre minimum length) with a bracket and with
another bracket fix another board (12 cm x 10 cm x 1 cm approx.) exactly 1 metre from the first
board. Pin a piece of white paper to the second board.
Your completed Solar Viewer should resemble the above diagram. It is now ready
to use. With your back to the Sun, place the rod over your shoulder, and aim the lens at the Sun so
that the shadow of the smaller board falls on the larger board. In the middle of this shadow
you will see a small (9 mm diameter) but perfect image of the Sun.
You can even see the sun-spots, perfectly focussed. Look an hour later, and you may be able
to see that image of the sun-spots has turned, as the Earth rotates. Look again a day or two
later and you may be able to see the changes in the pattern of sun-spots.
Having bought a pair of spectacles, you will, of course, have another lens .... so make
a second Solar Viewer and enjoy the Eclipse with a friend!