1. Telescopes Section 1-4

2. Telescope l Tele – distant, far l Scope- see l Invented in the 16 th century l First used by Galileo Who found moons around Jupiter l Optical telescopes collect light l Two types – Refracting – Reflecting

3. Refracting Telescopes l Use lenses to bend light l Larger lenses can gather more light l So get better picture l Largest is 40 inches across l Larger are not possible because the lenses distort the light.

4. Yerkes Observatory

6. Reflecting Telescopes l Use mirrors to collect light l First made by Newton l Mirrors can be larger l Largest is 200 in. at Mount Palomar near San Diego

8. l Put telescopes in domes with doors that slide open l Allow them to rotate and elevate l Point at the same point in the sky as the earth turns.

9. Multiple Mirror Telescopes l Large mirrors are hard to make. l Use several small mirrors that act together l Gather more light than a single mirror

10. Keck Observatory l 36 mirror hexagon segments- computer controlled l Largest optical telescope

11. The whole spectrum l Light is a small part of the electromagnetic spectrum l There are telescopes that detect other types of waves. l Radio telescopes- detect radio waves l Many stars give off mainly radio waves l Use computers to create an image from the waves. l Can use several together for even better images

12. Radio Telescopes

13. Arecibo

14. Infrared telecopes l Infrared is heat energy (warming lamps) l Dont travel through atmosphere l Put telescope on a satellite l IRAS Infrared Astronomy Satellite (1983) l ISO Infrared Space Observatory (1995) l Give us images of things that give off little energy, like new stars and nebula

16. Ultraviolet telescopes l Also need to be on satellites l Used to view our sun l Also found on the Hubble Space Telescope

17. X-ray telescopes l Also need to be on telescopes l Give information on life cycles of stars. l Uhuru 1970 l Chandra currently in l service

18. Hubble Space Telescope l Combination of telescopes – optical and ultraviolet l Has been repaired and upgraded twice l Giving scientists views of the universe they have never had before