spectroscopy

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).

SpectroscopyA 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.

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

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

Two modern applications of spectroscopy in space…

Mars Exploration MissionThe 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)

Cassini-Hyugen’s MissionMission: 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.

2 Basic Types of Spectra• Continuous- energy of all

wavelengths• Discrete- energy at a particular

wavelength– Emission or bright lines– Absorption or dark lines

Continuous Spectrum• Also called thermal

or blackbody spectra

• Spectra of stars, planets, moons

• Depends on temperature

Ex: sunlight passing through a prism

Hotter objectsShift toward this end

Cooler objectsShift toward this end

Shorter wavelength

Longer wavelength

Continuous Spectrum continued

Discrete Spectrum Absorption

Hot object

Cool, thin gas

SpectraAbsorptionspectrum

Ex: stars, planets w/ atmospheres, & galaxies

Each element has a unique signature of absorption lines. That pattern helps scientists identify the element(s).

Discreet spectrum-

Emission

Cold, empty space

Spectra

Emissionspectrum

Thin,hotgas

Again, the pattern of the lines determines the identity of the element.

Ex: comets, nebula & certain stars

Motion of Objects in SpaceBlue shift shows object ismoving 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.

Compare the dark lines in the middle spectra to the dark lines in the other two spectra.

Spectroscopy Lab

Determining the Spectraof Certain Elements

What type of spectrais shown here?

•Continuous•Absorption•Emission

What type of spectrais shown here?

•Continuous•Absorption•Emission

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

Light is just one portion of the electromagnetic spectrum.

Name 5 other parts of the EM spectrum.

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

No way! Were you sleeping?

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YES, we have a winner!

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Pat yourself on the back!

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That is a definite NO!

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