2. The Electromagnetic Spectrum Energy moves in uniform patterns called waves. The electromagnetic spectrum consists of the range of all possible frequencies of electromagnetic radiation. Wave lengths in this spectrum cover radio waves and light rays. Electromagnetic Waves: Do not need a medium (matter) to travel through

4. Amplitude: The amount of energy in a wave. The height of the wave above or below the rest position. Wavelength: The distance between two crests (top points) in a wave. Differing wavelengths can give waves unique behaviors.  Radio waves- waves with a wavelength the size of a house.  X-rays- waves with a wavelength the size of an atom. Frequency: The speed of a wave, measured in waves per second (or Hertz).  106.1 FM has a higher frequency (their waves move faster) than 94.5 FM but they are both radio waves, so their wavelengths are the same.

5. Stars: How do we know? use telescopes to observe and measure light from stars –magnitude = brightness of a star –absolute magnitude = actual brightness at a given distance –apparent magnitude = brightness as seen from Earth Doppler shift –analyze star spectrum –if shifted towards red, star moving away from Earth –if shifted towards blue, star moving towards Earth

6. NRAO/AUI/NSF6

7. 7 Gas Spectra Neon Sodium Hydrogen 656 nm 486 nm 434 nm Star spectrum – What gas is most likely present in this star?

8. Doppler Shift? Is this star moving towards or away from us?