1. Prologue Designer: Eric Kimsey
The following powerpoint presentation was designed to fulfill the requirements of the TAPS program at Jefferson Labs in Newport News, VA summer 2006.
This presentation was also designed to accompany and expound upon the topic of Light and the Electromagnetic Spectrum as required by the state of Virginia Physical Science SOL’s (PS.9c).

2. Spectroscopy A Tool of Astronomers Title slide
This ppt presentation was built to satisfy one requirement for the TAPS program at Jefferson Labs in Newport News, Virginia.

3. 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.
definitions

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

5. Studying an objects spectra can tell scientists the composition of an object, its temperature, its density and its motion.
Use of spectroscopy in astronomy.

6. Two modern applications of spectroscopy in space…

7. 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)

8. 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.

9. 2 Basic Types of Spectra Continuous- energy of all wavelengths
Discrete- energy at a particular wavelength
Emission or bright lines
Absorption or dark lines
Types of spectra
Continuous
Discrete
emission or bright line
absorption or dark line

10. Continuous Spectrum Also called thermal or blackbody spectra
Spectra of stars, planets, moons
Depends on temperature
Ex: sunlight passing through a prism
Most of these type of spectra are emitted from hot, dense objects. Hot objects emit EM radiation at all wavelengths. Temps above absolute zero will emit this type of spectrum. Blackbody is an object that absorbs all radiation falling on it (no reflection). When the blackbody is heated it emits light in a continuous spectrum.

11. Continuous Spectrum continued
Hotter objects
Shift toward this end
Longer wavelength
Shorter wavelength
Cooler objects
Shift toward this end
The way scientists use the spectrum to tell how hot an object is is determined by how much of a particular color is present. If more red is evident, then the object is a cooler object; if it shows more violet, then it is a hotter object.

12. Discrete Spectrum Absorption
Each element has a unique signature of absorption lines. That pattern helps scientists identify the element(s).
Ex: stars, planets w/ atmospheres, & galaxies
An absorption spectra forms when the spectra from a hot object passes through a cooler thin gas. When that spectra passes through the spectroscope it reveals a unique colored spectrum with dark lines. The location of the dark lines within that visible spectrum is a fingerprint that tells scientists what element is.
Spectra
Cool, thin gas
Absorption
spectrum
Hot object

13. Discreet spectrum- Emission
Again, the pattern of the lines determines the identity of the element.
Ex: comets, nebula
& certain stars
The radiation from a colder object in space that passes through a thin, hot gas emits a spectra that is the opposite of a absorption spectrum. These colored lines tell you the identity of the element according to their color & position in the EM spectrum.
Cold, empty space
Thin,hot
gas
Emission
spectrum
Spectra

14. 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.
Motion of objects in space. Self explanatory.
This shows a red shift meaning that the object is moving away from the observer.

15. Determining the Spectra of Certain Elements
Spectroscopy Lab
Determining the Spectra
of Certain Elements

16. Test your understanding...

17. What type of spectra is shown here?
Continuous
Absorption
Emission

18. What type of spectra is shown here?
Continuous
Absorption
Emission

19. Why does this picture represent just the continuous spectrum of light?
Credits:

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

21. Acknowledgements www.ipac.caltech.edu/Outreach/Edu/Spectra/spec.html

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

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

24. Pat yourself on the back!
Next question

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