RadiationRadiation

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Electromagnetic SpectrumElectromagnetic Spectrum

LightLight

A common term for A common term for electromagnetic electromagnetic radiationradiation, which travels in space as , which travels in space as waves.waves.

The human eye can only sense a The human eye can only sense a limited range of all the various limited range of all the various wavelengths of electromagnetic wavelengths of electromagnetic radiation. We only radiation. We only ““seesee”” visiblevisible lightlight..

Electromagnetic Radiation includes: Electromagnetic Radiation includes: (largest to smallest)(largest to smallest)

a.a. RadioRadio

b.b. MicrowavesMicrowaves

c.c. Infrared (IR)Infrared (IR)

d.d. Visible lightVisible light

e.e. Ultraviolet (UV)Ultraviolet (UV)

f.f. X-raysX-rays

g.g. GammaGamma

Examples of usesExamples of uses

UVUV – ( – (black light)black light). Some animals, . Some animals, including including birds, , reptiles, and , and insects such such as as bees, can see into the near , can see into the near ultraviolet. ultraviolet.

Many fruits, flowers, and seeds stand out Many fruits, flowers, and seeds stand out more strongly from the background in more strongly from the background in ultraviolet wavelengths as compared to ultraviolet wavelengths as compared to human color vision. human color vision.

X - RaysX - Rays Helps doctors diagnose disease and injury.Helps doctors diagnose disease and injury.

Radio WavesRadio Waves

Your favorite radio station, TV, Your favorite radio station, TV, entertainment, communication.entertainment, communication.

Gamma raysGamma rays

Used for the treatment of cancerUsed for the treatment of cancer Radiation therapyRadiation therapy detects the gamma radiation detects the gamma radiation

Gamma-ray Image with stowaways

Question: How does this Question: How does this (Electromagnetic Radiation) relate (Electromagnetic Radiation) relate

to astronomy?to astronomy? Stars, planets, and gas in space emit Stars, planets, and gas in space emit

electromagnetic radiation.electromagnetic radiation.

Each Each elementelement in the in the PeriodicPeriodic tabletable has it has it own unique own unique wavelengthwavelength and and frequencyfrequency..

Knowing its Knowing its wavelengthwavelength and and frequencyfrequency, we , we are able to determine are able to determine colorcolor and and compositioncomposition of stars, planets, ect… of stars, planets, ect…

Truck going Truck going through Radiation through Radiation Portal Monitor Portal Monitor

The Moon as seen in gamma rays by the Compton Gamma The Moon as seen in gamma rays by the Compton Gamma Ray Observatory. Ray Observatory.

Surprisingly, the Moon is actually brighter than the Sun at Surprisingly, the Moon is actually brighter than the Sun at gamma ray wavelengths. gamma ray wavelengths.

Electromagnetic Radiation in AstronomyElectromagnetic Radiation in Astronomy

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Electromagnetic radiation is Electromagnetic radiation is classified by its classified by its wavelengthswavelengths (distance from peak to peak).(distance from peak to peak).

Red lightRed light has longer wavelengths than has longer wavelengths than blue lightblue light..

Electromagnetic radiation can also be classified by itsElectromagnetic radiation can also be classified by its frequencyfrequency (the amount of occillations per a second.)(the amount of occillations per a second.)

Electromagnetic radiation travel at Electromagnetic radiation travel at the the speedspeed of of lightlight..

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What is the Doppler Effect?What is the Doppler Effect?

Change in the wave frequency that Change in the wave frequency that occurs when energy moves toward or occurs when energy moves toward or away from an observer or object, away from an observer or object, such as sound or light.such as sound or light.

What is a What is a ““red shiftred shift??””

The process of galaxies The process of galaxies moving AWAY from Earth, moving AWAY from Earth, resulting a in a longer resulting a in a longer wavelength.wavelength.

What is a What is a ““Blue ShiftBlue Shift??””

The process of galaxies The process of galaxies moving toward Earth, moving toward Earth, resulting in a shorter resulting in a shorter wavelength.wavelength.

Why are these Why are these ““shiftsshifts”” important in important in studying our universe?studying our universe?

Observations show that most Observations show that most galaxies are moving away from us, galaxies are moving away from us, thus proving that the universe is thus proving that the universe is expanding (BIG BANG THEORY).expanding (BIG BANG THEORY).

Can provide information about Can provide information about incoming objects (asteroids).incoming objects (asteroids).

Electromagnetic Spectrum and Electromagnetic Spectrum and AstronomyAstronomy

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Four Four Views of Views of Mars… Mars…