Transcript How do we know what we know about the universe?

Instruments of Astronomy
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We know what
we know about the
universe
by studying the energy
( light ) emitted by objects in
space.
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What do we call all the
energy/light we receive from
space?
The Electromagnetic
Spectrum
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http:/www.electro-optical.com/images/em_spect.gif
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What forms of energy/light can
actually reach most of the Earth’s
surface?
VISIBLE LIGHT
 RADIO WAVES
 SOME ULTRAVIOLET LIGHT

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What tools do we use to observe
these forms of energy that reach
the Earth’s surface?
* Telescopes*
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We gather and analyze all forms of
electromagnetic radiation from space
using different types of telescopes
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What types of telescopes do we
use to observe visible light?
Optical Telescopes:
Refracting
Reflecting
The purpose of optical telescopes
is to gather as much light as
possible
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Refracting Telescope
(Google-Images-Refracting Telescope)
This tool uses a convex lens
(objective) to collect and bend
light coming from an object.
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Reflecting Telescope
( Google-Astro-canada.ca)
This tool uses a concave mirror
(objective) to collect visible light.
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What type of telescope is used on
Earth to collect radio waves?
(AOL- Images-Radio Telescope)
The radio telescope.
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Radio Telescope
-uses a big curved dish to collect
the long radio waves
- focuses radio waves using an
antenna
- can be used during the day even
if cloudy
- - largest telescope used on Earth
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(Clip artJ0195812.wmf )
Why do astronomers use more
than one type of telescope to
observe energy/light coming
from space?
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

Most telescopes are only designed to
detect a particular portion of the
Electromagnetic Spectrum (EMS).
Due to the Earth’s atmosphere, not all
telescopes work best placed on the
surface of the Earth.
( Water vapor interferes with infrared,
ozone blocks most of the ultra-violet, the
atmosphere absorbs or scatters most xrays and gamma rays.)
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How do astronomers best
detect parts of the EMS which
do not entirely reach the
surface of the Earth?
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ORBITING
SATELLITES
(AOL-Images-Telescopes)
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What parts of the EMS are best detected
from space due to interference from the
Earth’s atmosphere?
Infrared
Ultra-Violet
X-Ray
Gamma Ray
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How are these parts of the
EMS detected from space?
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INFRARED


Uses optical reflectors with heat
detectors.
“sees” cool stars, objects and
dust associated with cold gas
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Ultra-Violet, X-Rays and Gamma
Rays
•
•
Data is sent back from telescopes
placed in space and then sent to
receivers on the ground for computer
analysis.
Due to the high energy of X-Rays
and Gamma Rays, they cannot be
directly collected since they go right
through the telescopes. As a result,
new technology has been developed
to measure their presence indirectly.
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Crab
Nebula
Optical
Radio
Ultraviolet
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X-ray
http://imagine.gsfc.nasa.gov/docs/teachers/lessons/xray_spectra/background-em.html
http:/wwwspitzer.caltech.edu/Media/guides/images/transmission.jpg
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