Download Electromagnetic Spectrum

Chapter 28.1
Electromagnetic
Spectrum
Scientists learn about the
Universe by collecting WaveEnergy from the
Electromagnetic Spectrum
The ElectromagneticSpectrum is a continuum
depicting the full range of
Electromagnetic Radiation,
with the longest wavelength at one
end, and the shortest at the other.
Electromagnetic Radiation is
energy in the form of a Wave,
resulting from the motion of
electric charges and the magnetic
fields that they produce.
Visible Light
Electromagnetic Spectrum
Increasing
Wavelength
Increasing
Energy
Objects in space emit energy in
several different Frequencies
and Wavelengths.
Wavelength
The Wavelength of a Wave
Red Light
Blue Light
The wavelength of each color of light is different
Frequency
The Spectroscope and the
Visible Spectrum
When light passes through a prism
and out again, they are refracted, or
bent, forming a band called the
Visible Spectrum.
Stars emit light that falls within
the visible spectrum.
Scientists use an instrument called a Spectroscope to
separate this starlight into its colors so that it can be
studied.
Spectroscopes break light into
three different types.
• Continuous Spectrum
• Emission Spectrum
• Absorption Spectrum
Each element gives a unique spectrum.
The position of the lines relative to one
another changes from element to
element and, as it turns out, from
molecule to molecule. In essence, the
emission spectrum is a fingerprint of the
element/molecule that generates it.
Emission Spectrum of Hydrogen
Absorption Spectrum of Hydrogen
By studying these different spectra, and comparing the
emission/absorption spectra of stars to those of gaseous elements in a
lab, astronomers can determine the types of elements that make up the
atmospheres of the stars that emitted the light.
Solar Spectrum
The Doppler Effect
Scientists use Spectral Analysis to not
only determine what gases are present
in stars, but also how they are moving
relative to the Earth.
This is possible because of a phenomenon
called the Doppler Effect.
Let’s look at some examples of
the Doppler Effect that you have
all experienced.
Fire Engine moving to the
right, and toward Person B
Fire Engine at Rest
Waves stretched
Person A
Person B
Waves
compressed
The Doppler Effect also applies
to Light.
Bright Line
Spectrum
Dark Line Spectrum
Because of Doppler Shift,
scientists have determined that
our Universe is expanding
Scientists have even been able
to use Doppler Shift to detect
the “wobble” of Stars with
orbiting massive planets.
Galaxy moving
away-Light
shifted toward
Red.
Galaxy moving
toward -Light
shifted toward
Blue.
Stars emit energy in wavelengths
that include…
1. Visible Light
2. Infrared
3. Ultraviolet
4. X-Rays
5. Gamma Rays.
X-Ray Black Holes
The Sun “viewed” through different wavelengths
H Alpha
UV
Gamma
X-Ray
M82 IR
M82 Radio
M82 Optical
M82 X-Ray
Astronomer view Space
through different types of
Telescopes
Optical Telescopes
1. Telescopes gather far more light than the
unaided eye can gather.
2. Telescopes magnify images.
Refracting Telescope
Refracting Telescope- Uses two lenses.
The Lense, at the front of the tube, gathers light.
The Eyepiece magnifies the image collected by the lense.
(limited in size by tendency of large lenses to bend)
Reflecting Telescope
Reflecting Telescope- Uses one large lense to gather
and focus light, then reflect the image to a small
mirror, then to an eyepiece on the side.
Since the lense is supported, reflecting telescopes
can be much larger.
Reflector
Scopes
Galaxy viewed through Optical wavelengths
Radio Telescopes
(technical term for really big satellite dishes)
Used to detect energy waves given off at frequencies
lower than visible light.
Lovell Radio Telescope
Cambridge Radio Telescope
Aricebo Radio Telescope
Galaxy viewed through Radio wavelengths
Other Types of Telescopes
COBE (Cosmic Background Explorer)
Cosmic Background Radiation From Big Bang
Milky Way Galactic Center
Compton Gamma Ray Telescope
ASCA
ASCA X-Ray Pulsar
ASCA X-Ray Black Hole
“Pillars of Creation”
Photographed by the Hubble Telescope (shown left)
IRAS Infrared Observatory
IR Man!
Infrared Milky Way Galactic Plain