Electromagnetic Spectrum - PowerPoint PPT Presentation

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Electromagnetic Spectrum

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Electromagnetic Spectrum Visible light and color Energy, frequency, wavelength Real-world uses Astronomy uses Fictional uses http://gallery.spitzer.caltech.edu ... – PowerPoint PPT presentation

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Title: Electromagnetic Spectrum


1
Electromagnetic Spectrum
  • Visible light and color
  • Energy, frequency, wavelength
  • A bit on telescopes
  • Uses

2
Why do we care about light?
  • Everything we know in astronomy comes from light
  • We only have physical samples from the Moon,
    Mars, and a couple comets
  • Even these we study using light

3
Electromagnetic Radiation
  • Radiation when things are sent out into empty
    space
  • EM radiation light
  • Nuclear radiation result of nuclear reactions,
    includes
  • Alpha particles (Helium nucleii)
  • Beta particles (positrons anti-matter
    electrons)
  • Gamma particles (gamma EM radiation)

4
http//www.lcse.umn.edu/specs/labs/images/spectrum
.gif
5
What is Light?
  • Electric and magnetic fields waving
  • Packets of energy called photons
  • Energy and wavelength determine what the light
    can interact with

6
http//www.yorku.ca/eye/spectrum.gif
7
False Color Images
  • Pictures attempt to translate invisible light
    to what we can see.
  • Representative color colors have meaning, such
    as specific non-visible colors or chemicals
  • Touch the Universe by Noreen Grice

8
High EnergyHigh FrequencyShort Wavelength
9
High EnergyHigh FrequencyShort Wavelength
  • Interacts with small things (cells, molecules,
    DNA)
  • Created by high energy / hot processes

10
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
11
?-ray (gamma) and X-ray
  • High energy, short wavelengths
  • On Earth radioactivity, some cancer treatment,
    broken bones, cavities
  • Astronomy high energy processes, hot
    environments, colliding stars, around black
    holes, gas around galaxies, the Sun

http//today.slac.stanford.edu/images/2007/swift-g
amma-ray-lg.jpg
http//www.atnf.csiro.au/people/mdahlem/img/xmmtel
.gif
12
Ultraviolet (UV)
  • Slightly higher frequencies and shorter
    wavelengths than humans can see
  • Some birds and insects can see in the UV
  • On Earth suntans, sunburn, cancer, can be used
    to sterilize equipment
  • Astronomy Used to study the Sun and other hot
    objects
  • Hubble is mostly visible, but does have one UV
    instrument

http//sohowww.nascom.nasa.gov/data/realtime/eit_1
95/1024/latest.html
13
Visible light and color
  • A small part of the total spectrum
  • Approximately 400-700nm, 4000-7000Å, violet to
    red
  • Each color the eye can see has a different
    wavelength.

14
http//solarsystem.nasa.gov/deepimpact/images/Spec
t-Prism-sm.jpg
15
http//wfc3.gsfc.nasa.gov/MARCONI/images-basic/spe
ctrum.jpg
16
Why do our eyes see with Visible light?
17
Atmospheric Windows
Wavelength, Energy
Frequency
High flying air planes or satellites
Need satellites to observe
18
Why do our eyes see with Visible light?
  • Atmospheric windows
  • Visible and Radio get through an Earth-like
    atmosphere
  • Wavelength determines size of things it can
    interact with
  • Due to evolution, sizes of our eyes, sizes of
    molecules in our eyes, we see visible light

19
Low EnergyLow FrequencyLong Wavelength
20
Low EnergyLow FrequencyLong Wavelength
  • Interact with larger things
  • Lower energy processes

21
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
22
Infrared (IR)
  • Slightly longer wavelength and lower frequency
    than the human eye can see.
  • Some animals including some snakes, some bats,
    and some insects can see IR.
  • On Earth IR goggles help firefighters, soldiers,
    and home insulation experts TV remote controls,
    Kinect
  • Astronomy IR travels through dust so is good to
    look at young forming stars. (e.g., James Webb
    Space Telescope, HSTs successor)

http//upload.wikimedia.org/wikipedia/en/c/cf/Ir_g
irl.png
23
Microwave/Sub-mm/Radio
  • Low energy, long wavelength
  • On Earth microwave ovens, cellphone signals,
    radio for stereos, (formerly) TV broadcasts, GPS,
    walky-talkies, satellite communications, GPS,
    weather radar, radar guns
  • Astronomy cool objects such as clouds of dust,
    gas clouds, entire galaxies, SETI, Cosmic
    Microwave Background (light from the Big Bang)

http//apod.nasa.gov/apod/image/0302/sky_wmap_big.
jpg
http//cache.eb.com/eb/image?id96170rendTypeId4
24
Bad Science Listening to Radio
  • Like all types of light, radio light is studied
    using either images or spectra (graphs of the
    colors brightness at each wavelength)

25
Nancay Radio Telescope
26
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
27
Each part of the wavelength tells us part of the
story.Must put together all wavelengths to
get the full story.
http//www.thunderbolts.info/tpod/2006/image06/060
123nebula.jpg
28
Example The Sun
  • http//sohowww.nascom.nasa.gov/data/realtime/realt
    ime-update.html
  • Putting these together helps us understand the
    layers of our dynamic Sun.
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