1. Chapter 21 Stars, Galaxies, and the Universe

2.  How do we study other stars in our galaxy if they are so far away?  We study the radiation that stars emit to find out more about them. Intro- duction

3.  Energy that can travel through space is called electromagnetic radiation.  Electromagnetic radiation can travel through empty space and travels in waves.  Electromagnetic radiation travels the speed of light. Electro- magnetic Spectrum

4. Electro- magnetic Spectrum Picture From: http://www.astronomynotes.com/light/s3.htm

5.  The electromagnetic spectrum is the full range of wavelengths of electromagnetic radiation. Electro- magnetic Spectrum

6. Diagram From: saturn.jpl.nasa.gov/mission/nav-uplink.cfm

7. Diagram From: http://zebu.uoregon.edu/~imamura/122/images/electromagnetic-spectrum.jpg

8. RADIO WAVES  Longest waves and less frequent than other waves.  Used for communication.  Radio telescopes used to collect radio waves.  Size of wave ranges from the size of a football field to the size of a football. Electro- magnetic Spectrum

9. MICROWAVES  Used in communication, weather maps, and as a heat source.  Size of wave ranges from 1 foot to 1 centimeter. Electro- magnetic Spectrum

10. INFRARED WAVES  Used as a source of heat.  Infrared telescopes used to detect infrared waves.  Size of wave ranges from a few centimeters to a few millimeters. Electro- magnetic Spectrum

11. VISIBLE LIGHT  Only energy we can see with the naked eye.  Refracting and reflecting telescopes use visible light.  Size of wave is microscopic. Electro- magnetic Spectrum

12. VISIBLE LIGHT  White light can be separated into the 7 different colors of light.  ROYGBIV  Red, Orange, Yellow, Green, Blue, Indigo, Violet  Spectroscopes used to break white light down into different colors. Electro- magnetic Spectrum

14. ULTRAVIOLET WAVES  Energy that is partially blocked by our atmosphere.  Common uses are tanning beds, disinfection, and black lights.  A large amount of UV light is harmful for living things.  UV cameras and telescopes use UV rays.  Size of wave is a few molecules. Electro- magnetic Spectrum

15. X-RAYS  Atmosphere reflects all X-rays back into space.  Commonly used to take pictures of bones.  Very harmful to living things.  X-ray telescopes use X-rays.  Size of wave is one molecule. Electro- magnetic Spectrum

16. GAMMA WAVES  Shortest wave with the most energy.  Atmosphere blocks all gamma rays from entering.  Deadly to living things.  Used for medical treatment.  Gamma telescopes study deep space, black holes, stars, etc.  Size of wave is smaller than an atom. Electro- magnetic Spectrum

18.  Most telescopes collect and focus different types of electromagnetic radiation.  Two main types of telescopes: reflecting and refracting telescopes.  Refracting telescopes use lenses that bend light to focus onto a small area.  Reflecting telescopes use mirrors instead of lenses but still focuses light onto a small area. Telescopes

20. The Keck Telescopes: Located in Mauna Kea, Hawaii

21. Hale 200-inch Reflector: Located in Mt. Palomar, California

22.  A building that contains one or more telescopes is an observatory.  Most observatories are on mountaintops where images are less blurred because of the Earth’s atmosphere. Observat- ories

23. A giant telescope relies on multiple dishes - Located in Socorro, New Mexico

24.  The shorter electromagnetic radiation is blocked by the Earth’s atmosphere.  Telescopes are placed on satellites to detect these short, high energy waves.  Hubble Space Telescope – reflecting telescope that detects visible light, infrared, and UV radiation. Satellites

25. Hubble Space Telescope

26. Compton Gamma Ray Observatory

27. Chandra X-ray Observatory A telescope penetrates space with X-ray vision

28. Spitzer Space Telescope It will spend 2 ½ to 5 years studying infrared light.

31.  Most large telescopes have spectrographs.  A spectrograph breaks the light up into colors.  Spectrographs reveal information about stars like their composition and temperatures. Spectro- graphs

32. Electromagnetic Spectrum Video Clip: http://lgfl.skoool.co.uk/keystage4.aspx?id=318 Electromagnetic Spectrum Video Clip