1. TELESCOPES

2. Where do we put telescopes to have the best viewing conditions? 1. On Earth: CLEARHIGHDRYCOLDDARK

3. Problem with Telescopes on Earth? Problem: Particles of all sorts in the atmosphere block and cloud the view Particles of all sorts in the atmosphere block and cloud the view

4. 2. In Space Solves atmosphere problem – CLEAR VIEW! Examples: Hubble, Cobe, Iras

5. Problem with telescopes in space? They’re in space! Hard to get to Hard to repair EXPENSIVE!!!

6. Functions of a Telescope 1. C ollect Light 2. M agnify Images 3. S eparate Distant Objects 4. U se as a Camera

7. OPTICAL TELESCOPES (USE VISIBLE LIGHT) Two types: 1. Refractor – BENDS LIGHT Invented by Hans Lippershey in 1608 Refined by Galileo in 1609

8. Galileo demonstrating his telescope

9. 2. Reflector – USES MIRRORS

10. Tololo Observatory - Chile

11. TYPE 1 – REFRACTING TELESCOPE How does it work? a. It bends light to create an image b. It uses two lenses 1. eyepiece (ocular) lens - small 2. objective lens - large

12. Draw it!

13. Type 2 – Reflecting Telescope a. Invented by Isaac Newton in 1668 b. Uses two mirrors Objective Mirror – Large Secondary (flat) mirror – Small Secondary (flat) mirror – Small c. Can be VERY LARGE 40 ft - 50 ft diameter objective mirror!

14. Draw It!

15. Advantages of a reflector 1. You only need to prepare one side of the mirror. (on a refractor the lens has two sides) – cheaper and distortion is less of a problem. 2. The whole back of the mirror can be supported, therefore can be made very LARGE

17. Non-optical Telescopes 1. Radio Telescopes a. Location – Earth (atmosphere does not affect radio waves) b. Structure – Large metal dish

18. c. Size – very large because radio waves have a very long wavelength

19. d. Arrays – sets of multiple radio telescopes that allow for more data to be gathered.

20. Ex – VLA (very large array) in Socorro, New Mexico 27 dishes. SETI– Search for Extra-Terrestrial Intelligence looking for intelligent radio signals looking for intelligent radio signals

21. Other Non-Optical Telescopes (all are satellites) a. Infrared – IRAS launched 1983

23. b. Microwaves – COBE Cosmic Background explorer. Discovered evidence of the Big Bang. Launched 1981

24. COBE Image of CBR

25. c. X-Rays – Chandra Launched 1999

26. Cassiopeia Super Nova

27. Black Hole

28. Crab Nebula

29. Saturn

30. d. Gamma Rays – GRO Gamma Ray Observatory

31. Milky Way