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Spectroscopy

Spectroscopy. A Tool of Astronomers. Definitions. Spectroscopy- the study of the light from an object. Spectrometer- an instrument which spreads out light making a spectra. Spectra- range of electromagnetic energy separated by wavelength.

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Spectroscopy

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  1. Spectroscopy A Tool of Astronomers

  2. Definitions • Spectroscopy- the study of the light from an object. • Spectrometer- an instrument which spreads out light making a spectra. • Spectra- range of electromagnetic energy separated by wavelength.

  3. Astronomers use spectroscopy because it allows them to determine the makeup of stars… without having to be present to take samples.

  4. Studying an objects spectra can tell scientists the composition of an object, its temperature, its density and its motion.

  5. Two modern applications of spectroscopy in space…

  6. Mars Exploration Mission The Mars Exploration Rovers were launched with the goal of searching for and analyzing rock and soils on Mars. They utilized several spectrometers to analyze samples. Mini-TES: miniature thermal emission spectrometer (examine rock, soil & atmosphere) MB: Mossbauer Spectrometer (examine mineralogy of rocks & soils) APXS: Alpha Particle X-ray Spectrometer (analyze elements in rocks & soils)

  7. Cassini-Hyugen’s Mission Mission: to gather information on Titan (Saturn’s moon). VIMS: Visual and Infrared Mapping Spectrometer (gather data about surface, rings & atmosphere of Titan and Saturn). CIRS: Composite Infrared Spectrometer (searches for heat and by that gather information on the object’s composition.

  8. 2 Basic Types of Spectra • Continuous- energy of all wavelengths • Discrete- energy at a particular wavelength • Emission or bright lines • Absorption or dark lines

  9. Continuous Spectrum • Also called thermal or blackbody spectra • Spectra of stars, planets, moons • Depends on temperature Ex: sunlight passing through a prism

  10. Continuous Spectrum continued Hotter objects Shift toward this end Longer wavelength Shorter wavelength Cooler objects Shift toward this end

  11. Discrete SpectrumAbsorption Each element has a unique signature of absorption lines. That pattern helps scientists identify the element(s). Ex: stars, planets w/ atmospheres, & galaxies Spectra Cool, thin gas Absorption spectrum Hot object

  12. Discreet spectrum-Emission Again, the pattern of the lines determines the identity of the element. Ex: comets, nebula & certain stars Cold, empty space Thin,hot gas Emission spectrum Spectra

  13. Motion of Objects in Space Compare the dark lines in the middle spectra to the dark lines in the other two spectra. Blue shift shows object is moving toward the observer. This shows the normal position or no motion. This shows a red shift meaning that the object is moving away from the observer.

  14. Spectroscopy Lab Determining the Spectra of Certain Elements

  15. Test your understanding...

  16. What type of spectrais shown here? • Continuous • Absorption • Emission

  17. What type of spectrais shown here? • Continuous • Absorption • Emission

  18. Why does this picture represent just the continuous spectrum of light?

  19. Light is just one portion of the electromagnetic spectrum. Name 5 other parts of the EM spectrum.

  20. Acknowledgements • www.ipac.caltech.edu/Outreach/Edu/Spectra/spec.html • www.astronomynotes.com/lights4.htm • http://saturn.jpl.nasa.gov/spacecraft/instruments-cassini-cirs.cfm • http://pmo-sun.uoregon.edu/~astrosites.html • http://marsrovers.nasa.gov/overview

  21. No way! Were you sleeping? Back to question #1

  22. YES, we have a winner! To next question….

  23. Pat yourself on the back! Next question

  24. That is a definite NO! Back to 2nd question

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