Radio Waves

Things That Produce Radio Waves

Radio waves are made by transmitters in many
devices that we use today like walkie-talkies,
police radios, and avalanche beacons. Radio stations
also generate radio waves of various frequencies from
their towers. In nature, radio waves are emitted
by all stars (including the sun), electrical sparks, and
lightning. This is why radio stations can experience
interference during electrical storms.
How They are Used
Radio waves are often used for
communication. Aside from transmitting
music from radio stations, radio waves are used by
the military, airports, and by safety officers to
relay information. Each organization uses different
frequencies of waves to avoid confusing
messages. Even astronauts can use radio waves
while they are in outer space to communicate with each other
and with NASA back on Earth.
Are They Dangerous?
Radio waves are very low in energy compared to other electromagnetic
waves. They are used so widely because they pose very little threat to
living things. There is some evidence, however, that large doses of
radio waves over a long period of time may cause certain types of
cancers like leukemia.

What Can We Learn from Them?

Everything in the universe that gives off light gives off radio waves.
This means that radio waves can help us find stars, galaxies, comets
and other celestial bodies. Special radio telescopes have been

developed to detect radio waves from stars that are far

too distant for our eyes to see. These telescopes look
like huge satellite dishes and can be up to 60 m wide!
Radio astronomy is extremely useful because it can be
used during the day, as compared to normal light
telescopes.

Microwaves

Things That Produce Microwaves

What makes microwaves? Microwaves are
basically high frequency radio waves. Many things
around us make microwaves like the microwave
ovens in our kitchens, cell phones, and other
transmitting devices. Many things in the universe
also emit microwaves like the sun and other stars.
Some of the biggest sources of microwaves in
the universe are supermassive black holes.
How They are Used
Microwaves have many interesting uses. The most well-known is for cooking food. Microwaves
cause water molecules to vibrate more quickly and, therefore, heat up. When you put food in
the microwave, you are really heating up the food's water molecules from the inside out!
Microwaves are also used in radar systems like speed sensors and weather predicting
systems. Radar works by sending out microwaves and seeing what they bounce off of and how
quickly they bounce back. Microwaves are also used to send messages from our cell phones.
Most people would have a hard time making it one day without microwaves!
Are They Dangerous?
Microwaves, just like any other type of electromagnetic energy, are made of radiation and
radiation can sometimes be harmful. It is thought that there may be a link between lots of
microwave exposure (like from cell phones) and certain types of brain tumors. Microwaves can
also cause cataracts or cloudiness in the lens of your eye if you are exposed to them too much.
What Can We Learn from Them?
Microwave telescopes can help scientists locate objects youcan't see with the human eye like
black holes. With a microwave telescope, black holes glow very brightly in space. Scientists

can also use microwaves to study the structure of galaxies because the center of each galaxy is
a massive microwave source. Our own galaxy, The Milky Way, is studied
using microwaves

Infrared

Things That Produce Infrared Waves

Have you ever felt heat radiating off a warm object? Well,
then you have felt infrared waves! Most infrared waves feel
warm to us and they are just barely
below our range of visible light.
Infrared waves are emitted by objects
that have heat like the sun, a fire, hot
chocolate, and even you.

What They are Used For

Infrared light is used for many things. First, it is
used for heat. Toasters, ovens and heat lamps
all work because of infrared waves. We also use
infrared waves for taking thermal pictures of
objects and for night vision goggles. Some
infrared waves are also used for
remote controls. When you push the button on a
remote, a beam of infrared light is sent to the device that you
are controlling.
Are They Dangerous?
The main concern with infrared light is that it is HOT! If you are around too much
infrared energy you may get burnt or overheated.

What Can We Learn from Them?

Infrared waves help scientists see
things in terms of heat. Infrared or
thermal photography can help us
study how fires burn, how animals
lose heat, and it can help us find objects in the universe.
For example, many nebulae are found using infrared
telescopes. Infrared telescopes also help us see through cloud cover so that we can
see the surface of planets like Venus, which has a very thick atmosphere.

Visible Light

Things That Produce Visible Light

Visible light is the range of electromagnetic waves that
humans can see. Anything that glows or gives off light
makes waves of what we call visible light. The sun, light
bulbs, candles and fire are all things that people
automatically think of when it comes to light, but visible
light comes from many sources and in many colors.
Some other sources of visible light include: television and
computer screens, glow sticks, and fireworks.

Visible light comes in all the colors of the rainbow. Each

color has its own special frequency and wavelength.
When all the colors are together, they make the normal
"white" light that we see.

What We Use it For

Visible light is extremely important to humans, we use it TO SEE! Without light, our
eyes would not be able to see images of anything. Aside from sight, there are other
important uses for visible light. We concentrate visible light to make lasers to use in

everything from surgery, to CD players to laser pointers. Visible light waves also
make our TV, computer and cell phone screens work.
Is Visible Light Dangerous?
Visible light is typically pretty harmless. However, some light can be so intense that
it can damage the receptor cells in your eye causing temporary or permanent
blindness. High powered lasers can also be damaging and will cause burns.
What Can We Learn From It?
Scientists can learn a lot about stars by observing the color
of light they give off. The color of a star's light indicates how
hot the star is and also the types of gases that it is made of.
We also study our own sun using visible light to understand
its structure. Satellites with cameras that capture visible
light are continuously used to study and monitor the surface
of our planet as well.

Ultraviolet Light

Things That Produce Ultraviolet Light

Ultraviolet light (or UV) waves are just beyond the range
that our eyes can see. These waves are generated a
great deal by our sun and other objects in the universe
like galaxies and comets. On earth, special light bulbs
are made that can emit UV light like the ones that are
found in tanning beds. "Black" lights also produce
ultraviolet light.

Ultraviolet Light

What is It Used For?

Ultraviolet light has many uses you may not be aware of. Due to
its high energy waves, UV light kills
bacteria and viruses. UV lamps are,
therefore, used to sterilize many
things such as surgical equipment
and food containers. Some
materials fluoresce or "glow" under
UV light. These materials are
incorporated into various types of
money, allowing counterfeit bills to be detected when ultraviolet
light is shined on them. UV light also stimulates our skin cells to
make vitamin D, which is critical in absorbing
calcium. Ultraviolet light is also used to whitenteeth.
Is It Dangerous?
Ultraviolet light has wavelengths that are so small that it penetrates our skin
and can affect the DNA in human cells. Consequently, UV light from the sun is a
major cause of skin cancer. Luckily, the Earth's ozone layer blocks out most of the
sun's UV rays. However, people still need sunscreen to block the portion of the
waves that make it through the atmosphere.
What Can We Learn From It?
Many of the objects in the sky emit ultraviolet light and
scientists put UV telescopes on satellites to study these
far away sources of light. The light
of young stars, for example, is
mostly UV light. So with the help
of a UV telescope, galaxies can
look very different because we can
actually see all of their stars. UV
telescopes also help us study the structure of the sun because
the hotter parts of the sun produce the

X-Rays

Things That Produce X-Rays

X-Rays are emitted from objects have that a LOT of energy. Many things in the
universe have so much energy that they produce X-Ray waves. These objects

include the sun, supernova remnants, black holes, neutron stars

and even some comets. On earth, we have developed machines
that can produce X-rays that we use for various purposes. Even
though our sun emits large amounts of X-rays, we are protected
from this radiation because it gets absorbed by our atmosphere.

What They are

Used For

X-Rays have
their extremely
atom). As a
inside things.
view tissues
X-rays also
airports,

the ability to penetrate things due to

small wavelengths (about the size of an
result, we mostly use X-rays to see
X-ray machines are used medically to
inside the body like people's skeletons.
have important security applications at
events centers, and customs offices.

Are They Dangerous?

X-Rays are very high energy waves and will
cause tissue damage if you are exposed to
them for too long. Eventually, X-ray exposure
can create tumors and various types of cancer.
This is why heavy lead shields are used when
X-rays are taken. The shields
reduce the area that is
actually exposed to the
radiation. Technicians who work in X-ray labs protect
themselves with larger shields or by leaving the
room.
What Can We Learn From Them?
X-rays are produced from objects in the universe that are extremely hot or high
energy. Astronomers use X-rays to study black holes, comets, and the gases of
supernova remnants. Some of these objects can't even be seen using regular light
telescopes. X-rays can also be used to study the auroras that occur near the poles
of the Earth.

Gamma Rays

Things That Produce Gamma Rays

Gamma rays have the highest frequency and most energy
out of all the electromagnetic waves. They are produced
only by the most violent and energetic events. In space,
gamma rays are emitted as huge gamma ray bursts, by
supernovas, neutron stars and around black holes. Gamma
ray bursts can release more energy in 10 seconds than the
sun will release in 10 billion years! Here on Earth, gamma
rays are generated by nuclear explosions and some radioactive materials.
What They Are Used For
Gamma rays have amazing medical applications. These high
energy waves are used for radiation therapy on cancer patients
because they can kill the cancer cells. In this type of therapy,
gamma rays are focused just on the area where the cancer cells
are. Doctors can also use gamma rays for diagnostic testing. In
this case, a slightly radioactive substance is introduced to a
person's body. Doctors can then track the radiation in order to
see how certain organs are functioning. Gamma rays are also
efficient at killing bacteria and are used for sterilizing surgical
instruments and food.
Are They Dangerous?
Due to their extremely high energy, gamma rays are very dangerous.
Even small doses can lead to cancers and cell damage. If unborn or
young children are exposed to gamma ray radiation, serious mutations
can occur. When nuclear bombs were used in the past, it was the
radiation that had the most deadly effect, not the explosion itself.

What We Can Learn From Them

Gamma rays are useful in studying very distant objects in the

universe. Even events that are 12.8 billion light years away can
be detected by gamma ray telescopes. Astronomers use gamma
ray telescopes to study distant gamma ray bursts, the formation
of black holes, and the structure of supernova explosions.
Gamma rays can also be used to study the composition of planets
and determine which elements they are made of.