Download Section 22.1 Earth Science

Section 22-1 Study Guide
Radiation from Space
Ms. Grady
Light from the Past
 When you look at
a star, the light that
you see left the star
many years ago.
 Light travels fast
and distances
between objects in
space are so great
that it take millions
of years for the
light to reach Earth.
Light and other energy
leaving a star are
forms of radiation.
Radiation is energy
that is transmitted
(sent out/put out) from
one place to another
by electromagnetic
waves. See picture
below.↓
Because of the electric
and magnetic
properties (belongings)
of this radiation, it is
called electromagnetic
radiation.
Example:
Electromagnetic waves
carry energy
(force/power) through
empty space and
through matter
(anything that has mass
and takes up space).
When you turn on
the radio.
When you look
down a microscope.
When you have an
X ray taken.
Electromagnetic
radiation is
everywhere around
you.
The arrangement of electromagnetic radiation is called the Electromagnetic spectrum.
The Electromagnetic spectrum is arranged by wavelengths + frequency. The shorter the
wavelength = the higher the frequency.
.
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Forms of electromagnetic radiation differ
(change) in their frequencies
(occurrence/rate).
Frequency is the number of wave crests
that pass a given point per unit of time.
Electromagnetic Radiation
Sound waves
are a type of
mechanical
wave.
We hear the voices
of astronauts while
they are in space
because astronauts
speak into a
microphone.
The radio waves travel through
space and through the Earth’s
atmosphere.
Two types of
electromagnetic
radiation are:
 Radio waves
 Visible light
from the sun.
They cannot
travel through
empty space.
These sound waves
are converted
(changed) into
electromagnetic
waves called radio
waves.
They are then changed (converted)
back to sound waves by electronic
equipment and audio speakers ↓.
Other examples of
electromagnetic
radiation are:
 Gamma rays
 X rays↓
 Ultra violet waves
 Infrared waves
 Microwaves↓
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Radio waves
microwaves
Communication Is an oven to
on – radio
heat food.
waves, TV, radar
signals
Communication
on remote
control
Infrared waves
= heat
Thermal images
communication
Visible
lights
Can be
seen by
human
eyes colors
Not affected by
atmosphere
Ultraviolet rays
Sterilize
(kill
bacteria)
but also
kill good
living
cells.
Example,
Sunburn
→skin
cancer
X-rays
Few
penetrate
(get through)
Earth’s thick
atmosphere
Gamma
Rays
Radiation
treatment to
kill cancer
cells
(gamma
treatment)
Speed of Light
Speed of light (speed of all electromagnetic waves) = travel at 300,000 km/s in a vacuum (km/s=
kilometers/second).
Visible light and other
forms of electromagnetic
radiation travel at this very
fast speed.
The universe is so large that
it takes millions of years for
the light from some stars to
reach earth.
When electromagnetic light
reaches earth, scientists use
it to learn about the star it
came from.
For example, one tool for
studying electromagnetic
radiation is the telescope.
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Optical Telescopes →Uses light to produce (show) magnified (overblown) images of faraway
objects. Telescopes use radiation spectrum to explore the space.
Light is collected by an
objective lens or mirror.
It then forms an image
(picture) at the focal point
of the telescope.
A focal point is the point
where the light is bent by
the lens or reflected by the
mirror comes together to
form an image (picture).
The eyepiece increases the
image for the eyes.
Refracting telescope – uses convex lens that gathers light (+) plus one (1) concave lens (eyepiece)
that brings image to the eye.
Refracting –
lights bend when
they pass through
lenses.
Reflecting –
(lights) hit
(mirror) and
come back
Reflecting telescope - uses a curved (concave) mirror, and a flat mirror, and a convex lens.
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Concave
Convex
Concave surface – curves inward
Convex surface bulges outward
Concave lens causes light rays to spread
apart or diverse
Concave mirror causes light rays to meet or
converge
Convex lens causes light rays to meet or
converge
Convex mirror causes light rays to spread
apart or diverge.
Observatories = buildings that have dome-shaped roofs for viewing the sky.
Not all telescopes are located in observatories. The Hubble Space Telescope is an example of one.
The Hubble Space Telescope
 High quality images
 When the largest mirror of this
reflecting telescope was shaped,
a mistake was made.
 Launched in 1990 by
the space shuttle
Discovery.
 Repaired (fixed) in 1993
for because the mirror did
not work properly
 In 1997 and 1999, two
more missions to fix Hubble
were carried out (took
place).
 After it was fixed, Hubble
could view a large cluster of
galaxies known as Abell
2218.
Large Reflecting Telescopes
Early 1600sLippershey Gailileo – was the first person who used a
telescope to observe. He invented the telescope.
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The Keck telescope mirrors (located in Hawaii, USA)
 Are built out of many small mirrors that are pieced together.
 Have segmented mirrors (mirrors put together in parts) 10 m wide.
Fun fact – In 2000, the European Southern Observatory’s telescope
(located in Chile, South America) consisted of four 8.2 – m reflectors.
This is the largest optical telescope.
Active and Adaptive Optics
Active optics – computer corrects images
(pictures) that are distorted (unclear) by
temperature changes → mirror errors
Adaptive optics –laser probes atmosphere
and transmits (sends out) information to a
computer about air turbulence
(commotion/disturbances).
The computer then fixes (corrects) the
telescope’s mirror thousands of times per
second.
Telescope images (pictures) are clearer
(easier to see) when corrections for air
turbulence, temperature changes, and mirrorshape changes are made.
Radio Telescopes - can be used without light and in bad weather.
Radio waves are an example of long – wavelength
energy in the electromagnetic spectrum. They pass
freely though the Earth’s atmosphere
Picture of Radio telescopes
Radio telescopes study radio waves traveling
through space. They are useful 24 hours a day
under most conditions. The metal dish gathers
radio waves onto an antenna. A computer produces
(makes) images.
Infrared Telescopes
 Example: IRAS – was the first infrared telescope.
 Only stars in space give off visible light – all objects give off heat (infrared
waves)
 Infrared telescopes carried into space.
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