How we study the visible light

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How we study the visible light

• The visible light spectrum
• Each color specific wavelength
• Each star emits specific wavelengths.
• Astronomers use the spectrum of a star to
  determine its composition

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3 Kinds of Spectra
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SHORT wavelengths BLUE color LONG wavelengths
RED color
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DOPPLER SHIFT

• Change in WAVELENGTH caused by a change in
  POSITION

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Doppler Shift

• APPROACHING objects show a DECREASE in WAVELENGTH
• RECEDING (moving away) objects show an INCREASE
  in WAVELENGTH

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SHORT wavelengths BLUE color LONG wavelengths
RED color
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RED SHIFT VS. BLUE SHIFT

• Approaching objects show a BLUE SHIFTED spectrum

Objects moving away show a RED SHIFTED spectrum
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BLUE-SHIFTING STAR (Moving Towards Us)
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RED-SHIFTING STAR (Moving Away From Us)
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Star MOVING AWAY from us. (RED-SHIFTING)
REFERENCE SPECTRUM
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• Studying the Stars
• EM Spectrum

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Electromagnetic Spectrum

• Radio Waves
• Microwaves
• Infrared Waves (IR)
• Visible Light
• Ultraviolet Waves (UV)
• X-Rays
• Gamma Rays

• Longest Waves
• Shortest Waves

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The Electromagnetic Spectrum
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Longest ?
Shortest ?
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Which EM energy reaches our surface?
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VISIBLE VS. INFRARED
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VISIBLE VS. ULTRAVIOLET
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Visible
X-Ray
I R
Radio
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I R
Visible
UV
Radio
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Radio Astronomy
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40 meter radio telescope
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Radio Telescope Imageof Galaxy M81
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VLA Image
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Very Large ArraySocorro, NM
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NRAO Greenbank, West Virginia
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Pulsar Radio Image
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Janskies
Minutes
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Navy Radio Telescope
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GBT
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25 Meter Radio Telescope
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VLBA Radio Telescope
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Very Large Baseline Array Sites
Hawaii California Washington
Iowa New Hampshire
Kitt Peak, AZ
New Mex. Texas New Mex. Virgin
Islands
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RATs (Radio Astronomy Team)

• Meets every Thurs at GPN Planetarium

The GPT
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Small Radio Telescope