MAKING A TELESCOPE MIRROR

Press, 12 May 1984, Page 19

MAKING A TELESCOPE MIRROR

How to make your own telescope mirror. First, set up an old gramophone with its turntable horizontal. Use a spirit level for this. Next, centre an old cheese flan dish or similar on the turntable and hold in place with plasticene. With the turntable spinning, Araldite or a similar resin can be

fed into the dish. This will adopt a parabolic shape. Keep the dish rotating at constant speed until the resin is set hard. A dust cover above the dish would be a good idea. After the resin is set, the surface can be lightly polished and a reflecting substance applied. It is then suitable for use in an astro-

The annual conference of the Royal Astronomical Society of New Zealand will be held this week-end at the University of Canterbury. Talks will range from modern mathematical theories of the origin of the universe to recent advances in the geology of the planets, and plans for observing Halley’s Comet. New Zealanders over the years have made many contributions to man’s understanding of the heavens: one forgotten contribution which has just come to light is described below.

nomical telescope, although a number of trials might be necessary to achieve a true surface. The focal length at 33 r.p.m. is about 40 centimetres; at 45 r.p.m. it is 22 centimetres. Do not attempt to do this with water in the dish because of the risk of electric shock.