1. Studying the Universe

2. Telescopes  Telescopes aid astronomers in 2 ways Gather more light than the naked eyeGather more light than the naked eye Magnify imagesMagnify images

3. Telescopes BBBBest locations: Mountain peaks BBBBecause of thinner air and high elevations Desert climates DDDDry, clear skies Remote areas NNNNo city lights

4. Telescopes  Optical Use lenses or mirrors to gather and focus starlightUse lenses or mirrors to gather and focus starlight Kept in domes to protect from the weatherKept in domes to protect from the weather Light gathering power depends on the area of the lens or mirrorLight gathering power depends on the area of the lens or mirror

5. Refracting Telescope  Two lenses Objective lens (end away from your eye)Objective lens (end away from your eye)  Gathers starlight and bends it to form an image at the other end of the scope Eyepiece lensEyepiece lens  Magnifies the image for your eye

7. Reflecting Telescopes  One large curved mirror gathers and focuses starlight  The large mirror is the objective  Has a secondary mirror to reflect the image to the observer  Also has an eyepiece lens to magnify the image

9. Radio Astronomy  The study of radio waves given off by objects in space  Radio waves can pass through clouds of fine dust between stars (light rays can’t)  Can also be used during the day, when the stars can’t be seen

10. Radio Telescopes  Look like satellite dishes used for TV  Made of solid metal or wire mesh  Collects and focuses radio waves  Radio waves have longer wavelengths, so radio telescopes must be bigger than opticals

11. MMT MMMMMT = multiple mirror telescope SSSSeveral mirrors take the place of a single large mirror LLLLess expensive to build than single mirror

12. Hubble Space Telescope  In orbit around Earth to avoid clouds and be closer to far away objects  Misshapen main mirror and other mechanical difficulties made it less effective  Computers have provided image correction technology so the telescope can be used

13. Studying Energy  Stars emit light we can see….they also emit energy we cannot see  Electromagnetic energy – includes light, x-rays, radio waves, microwaves  Each type of energy has a different frequency and wavelength  All have the same velocity = 300,000 km per second

14. Electromagnetic spectrum = the range of wavelengths from radio waves to gamma rays

15. Describing Energy  Energy travels in waves…  Frequency = the number of waves that pass by a point in one second  Wavelength = distance from peak to peak or trough to trough  Frequency and wavelength are inversely proportional (as one goes up, the other goes down)

16. Visible Spectrum  Visible spectrum = the range of wavelengths we can see  Each color of the rainbow has a different wavelength and frequency  All of the colors of the rainbow make up “visible” or “white” light  Red has a long wavelength, which means it bends less when passed through a prism

18. Visible Spectrum  Spectroscope = a prism with a tiny viewing telescope  Separates light into its different colors  Spectrograph = prism with a lens and a camera, which records the spectrum

20. Visible Spectrum  Seeing the colors of light allow astronomers to determine which chemical elements are present in the star’s outer layers  Spectra also allow astronomers to determine if the star is moving towards us or away from us

21. Kinds of Visible Spectra  Continuous spectrum – unbroken band of colors, source is sending out all visible wavelengths of light  Can be produced from a glowing solid (light bulb)  Can be produced from a glowing liquid (molten iron)  Can be produced from the hot, compressed gases deep inside a star

23. Kinds of Visible Spectra  Bright line spectrum – unevenly spaced series of lines of different colors and brightness  Source emits only certain wavelengths of light  aka – emission spectrum  Each element (as a gas) has a unique combination of colors

24. Kinds of Visible Spectra  Dark line spectrum – continuous spectrum with dark lines where light is absorbed  Dark lines are in the same place as the bright lines  Form when light emitted by a star passes through a cooler gas  Gas absorbs the same wavelengths it would give off if heated  aka – absorption spectrum  Used to identify the element

27.  Emission spectra box  Tube is filled with a single element in the gaseous state  Electricity heats up the gas  The gas emits certain wavelengths of light  Combo of colors tells you what element you have