The Electromagnetic
Spectrum
By
Katie Markham
Visible Light
• There is a very small section of the
electromagnetic spectrum that the
human eye can perceive. It is known
as the visible color spectrum, or what
most refer to as the rainbow. The
colors that we, here on earth, label as
black are actually what make up the
rest of the spectrum.
Perception
• The section that the human eye is
able to perceive starts around
400nm (blue) and ends around
700nm (red). Of course every
persons perception is different.
The Rainbow
• Just as in most other things the
electromagnetic spectrum has a unit
of measure, nanometers among
others. Similar to the rainbow that we
know the visible color spectrum starts
as “red” and end as “blue”. What
proceeds that is the imperceptible to
us such as, infrared, ultra violet, micro
waves, x-rays, radio, and gamma
waves.
Radio Waves and Astronomy
• One of the most important advances
in astronomy was the radio telescope.
It allows scientists to discover other
galaxies, planets, and stars without
the use of the human eye. These
telescopes are designed to pick up
strong signals or radio waves, which
make it possible to study other
galaxies.
Radio Transmission
• As previously stated, the electromagnetic
spectrum has many measurements. Our
atmosphere, here on earth, is only able to
emit certain parts of the spectrum. Radio
waves are un-seeable to the human eye
but are what is used for electronic
communication.
Microwaves
• Scientist theory of “The Big Bang” is
strongly supported by microwave
evidence. In astronomy they have a
specific term for this radiation called CMB
or Cosmic Microwave Background. Using
this they can go back and find out what
really happened with the gigantic
shockwave. They are also used in our
microwaves to super heat food. Once
again they are invisible to the human eye.
Infrared Radiation
• Infrared radiation is mostly derived from
massive amounts of heat. Like radio
waves, satellites have been sent in to
space to pick up radiation caused by heat
and rapid movement of molecules and
atoms. The European Space Agency
(ESA) has an entire Infrared Space
Observatory which mainly focuses on
“dusty regions on space”. These regions
are easily studied with today’s technology
and satellites.
Ultra Violet Radiation
• This type of radiation is one of the closest
to visible light and is on the blue end of the
spectrum. With the assistance of
explorers data can be collected using ultra
violet rays. Temperature, distance, and
composition of objects and places in
space can all be determined. Ultra Violet
radiation is not emitted into our
atmosphere, and it is also invisible to us.
X-rays
• X- ray are useful to study things with high
energy levels. There are specific stars
called Neutron Stars that are easily seen
using x ray technology. These stars are
located around black holes therefore
producing massive amounts of energy.
This is the same radiation that doctors use
to in vision broken bones.
Gamma Rays
• Objects containing even more energy are
amounted using gamma rays. So in a
sense they are their own unit of measure.
With the development of Compton
Scattering these rays can be very
accurately measured. Basically what that
is a theory that some objects molecules
can in fact interact with gamma rays.
Spectroscopes
• The Main job or spectroscopes is to separate
the different colors of light generating off of
stars. The way that they work is by having
light travel through a lens. Then be refracted
though a prism. After that it travels through
another lens, once again being refracted.
Finally the light is transposed on to a
photographic plate. Spectroscopes allow
astronomers to see chemical composition of
atmospheres, pressure, magnetic field and
temperature of stars. Distances can also be
concluded.
The After Math
• The product of these scopes are three
different types of visible spectra. All within
the visible light spectrum. They are; the
continuous spectrum, the bright- line
spectrum, and the dark- line spectrum.
Continuous Spectrum
• There are three materials that this is able
to see. Both glowing liquids and solids
and the super hot gases compressed in a
star.
Bright- Line Spectrum
• The way it is projected this spectra looks
like a bunch of separated lines. This part
is designed to only show some types of
brightly colored lines. Chemical gas and
vapor clouds are what causes this
spectrum. Apparently each element has
its own specific bright- line spectrum.
Dark- Line Spectrum
• Like the bright- line spectrum this one also
absorbs light from elements. But, the way
it interprets the light after it has traveled
through a cooler gas than it had been
traveling in. The way to find out what
particular gas the wavelengths traveled
though is that, every gas absorbs the
exact same amount of wave lengths if it
were heated. Every gas has different
wave length absorption.
Spectra in the Stars
• With the combined help of the bright and
dark line spectrum scientists develop
atmospheric compositions of far of starts
and planets. Some planets however, do
not contain gases that show up using
spectra scopes. Scientists at first were
puzzled by this, until they managed to
draw the conclusion that their atmosphere
are made of unknown gases to us,
because our atmosphere doesn’t contain
them.
Colors of Stars
• Just by looking up at the sky you can tell
which are the hotter and which are the
colder stars. Likewise to a camp fire the
hottest stars are a blue-ish white color,
and the cooler ones are of a red shade.
ROYGBIV (red, orange, yellow, blue,
indigo, violet) is the basic order from
coolest to hottest stars. These clues also
help astronomers determine the chemical
composition of the stars.
The Doppler Effect
• This is used to describe many things in the
electromagnetic spectrum. It deals mostly
with blue and red shifts. When frequency
appears to increase it is called a blue shift.
But when it is drawn away or decreases it
is called a red shift. Astronomers mainly
study this shift in stars, galaxies and
clouds. The shift is really the difference
between frequency and wave length.
• http://sci2.esa.int/interactive/media/flashes
/2_2_1.htm
Doppler Effect Cont.
• There are several classifications of red
shifts. Gravitational Redshifts are when
change is radiation is thought to be to
large gravitational fields. Cosmological
Redshifts are related to “The Big Bang”
and the continues expansion of space.
Not only is this effect witnessed in out side
of the ozone, it is also here on earth.
The Doppler Effect on Earth
• On Earth the most commonly sighted or
rather heard Doppler Effect is within sound
frequencies, such as the path of an
ambulance. The sound of he siren seems
to change frequencies so that is the
lengthening and shortening of the sound
waves as they are shot off of other
objects. This theory was presented by
Christian Doppler a mathematician and
physicist.
Bibliography
• Doppler Effect.
http://sci2.esa.int/interactive/media/flashes/2_2_
1.htm
• Electromagnetic Spectrum.
http://en.wikipedia.org/wiki/Electromagnetic_spe
ctrum. June 2006
• Science Discoveries Isaac Newton and Gravity.
Chelsea House Publishers.12-13
• Spaulding, Nancy E., and Samuel N. Namowitz.
Earth Science. Evanston Illinois: McDougal
Littell, 1994. 370-375.