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?
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http:/wwwspitzer.caltech.edu/Media/guides/images/transmission.jpg
What forms of energy/light can
actually reach most of the Earth’s
surface?
Visible Light
 Radio Waves
 Some UV, Microwave and Infrared
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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:
Two Types of Optical Telescopes:
1. Refracting 2. 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?
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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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).
X-ray
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Radio
Due to the Earth’s
atmosphere, not all
telescopes work best
placed on the
surface of the Earth.
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Water vapor
interferes with
infrared
Exception: South
Pole is very dry
•Ozone blocks
most of the
ultra-violet rays
•The atmosphere
absorbs or
scatters most
x-rays 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
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Uses optical reflectors
with heat detectors
“Sees” or detects cool stars,
objects and dust associated
with cold gas
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Cold gas
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.
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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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Gamma Rays
Crab
Nebula
Optical
Radio
Ultraviolet
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http://imagine.gsfc.nasa.gov/docs/teachers/lessons/xray_spectra/background-em.html
X-ray
Milky Way
http://mwmw.gsfc.nasa.gov/mmw_telescope.html
http://www.nasa.gov/mission_pages/spitzer/multimedia/20080603a.
html