Telescopes Today: Practice Problem Solutions

1. A refractor uses a lens to bend light to a focus; a reflector uses a curved mirror.

2. A mirror can be supported from behind and so can be made much larger; a very large lens would sag under its own weight.

3. (100 / 5) squared = 400 times.

4. To get above Earth's air, which blurs images and blocks some kinds of light (such as X-rays and most infrared).

5. Infrared.

6. A flexible mirror that changes shape hundreds of times a second to cancel the blur caused by Earth's air.

7. A pair of binoculars (7x50 or 10x50), then perhaps a Dobsonian reflector.