Visible Light and Beyond “White light” is made up of a rainbow of colors, each with a different wavelength.

William Herschel Discovery of Infrared Radiation

Build your own Herschel demo

The full electromagnetic spectrum … Making Light of it All!

The Electromagnetic Spectrum Our eyes see only part of the electromagnetic spectrum…

Riding the Wave  Light is a transverse wave of electromagnetic energy  The wavelength (and, reciprocally, the frequency) of light defines its radiation band (X-ray, or Visible, or Infrared, or …)

Light has a dual nature: It exhibits both wave-like and particle-like properties

FORMULA CONNECTING WAVE & PARTICLE PROPERTIES OF EM RADIATION: E = h c / E=energy per photon (joules, J) h=Planck’s constant c= speed of light (m s -1 ) = wavelength (m)

Low-energy Light  Infrared Thought of as “heat,” common in daily livesThought of as “heat,” common in daily lives  Microwaves Used for communication, cookingUsed for communication, cooking  Radio Wavelengths of centimeters to kilometersWavelengths of centimeters to kilometers Great for transmissions that need to go far and penetrate buildingsGreat for transmissions that need to go far and penetrate buildings

High-energy Light  Gamma Rays Radioactive atoms, nuclear power plantsRadioactive atoms, nuclear power plants  X-Rays Penetrate soft tissuePenetrate soft tissue  Ultraviolet Tans and sunburns, mostly stopped by atmosphereTans and sunburns, mostly stopped by atmosphere

Temperature determines the main type of radiation emitted … (left to right: Compton, Chandra, Hubble, and Spitzer space observatories)

“Invisible” Light in Astronomy Each part of the spectrum provides a piece of the puzzle in understanding our universe.

The Pinwheel Galaxy – M101

Multi-wavelength astronomy Constellation Orion left: visual-wavelength view right: far-infrared view An object can appear radically different depending on the type of light collected from it:

VisibleNear InfraredMid-Infrared  Visible: dark nebula, heavily obscured by interstellar dust  Near-IR: dust is nearly transparent, embedded proto-stars can be observed  Mid- and far-IR: glow from cold dust is directly observable

EARTH ATMOSPHERIC OPACITY VERSUS WAVELENGTH

There’s a problem for IR astronomy...  Earth’s atmospheric water vapor absorbs almost all incoming infrared radiation  Even mountain-top observatories get a limited view of the infrared universe

thermal-IR image of Earth from a weather satellite

View of troposphere / stratosphere boundary from above

And a Solution...  High-flying aircraft -- above 40,000 ft -- can observe most of the infrared universe  Airborne infrared telescopes can be more versatile -- and much less expensive -- than space infrared telescopes NASA’s Kuiper Airborne Observatory (KAO) C-141 with a 36-inch telescope onboard, based at NASA-Ames near San Francisco, flew from ,

Further information:  SOFIA Science Center home page  Spitzer Space Telescope’s award-winning infrared tutorial (includes instructions for home-made Herschel demo)

Each part of the spectrum impacts our daily lives… “Invisible” Light in Society Microwave ovens Communications Remote controls X-rays Sunscreen

We collect light from distant objects, and bring together researchers from many disciplines. The Tools of Our Search

Where did we come from? What is our destiny? Are we alone?

Our Place in the Universe

Are we alone? Searching for Life

JUPITER – heat from formation still escaping

The Orion M42 star-forming region (left to right: visible-, near-IR, mid-IR)

To find the earliest galaxies, we will need to explore the universe in the infrared. Looking Back in Time

Active Astronomy (“AA”) classroom kit Middle School physical science, High School physics 4 activities comparing and contrasting 4 activities comparing and contrasting visual & infrared light Teachers’ guide including curricular material, Teachers’ guide including curricular material, pre-/post-tests, parts list available at:

Resources  SOFIA Active Astronomy my.html my.html  Stanford Solar Center Spectrascopes and Colors of the Sun video  The Dynamic Sun  Project Spectra  Project Spectra 12/project-spectra/

Further information: SOFIA Science Center home page SOFIA Science Center home page Spitzer Space Telescope’s award-winning Spitzer Space Telescope’s award-winning infrared tutorial: (includes instructions for home-made (includes instructions for home-made Herschel demo)