How do we know what
we know about the
universe?
By studying the energy ( light )
emitted by objects in space.
What do we call all the
energy/light we receive
from space?
The Electromagnetic
Spectrum
http:/www.electro-optical.com/images/em_spect.gif
What forms of energy/light can
actually reach most of the Earth’s
surface?
VISIBLE LIGHT
 RADIO WAVES
SOME ULTRAVIOLET LIGHT


http:/wwwspitzer.caltech.edu/Media/guides/images/transmission.jpg
What tools do we use to
observe these forms of
energy that reach the
Earth’s surface?
* Telescopes*
What types of telescopes do we
use to observe visible light?
Optical Telescopes:
Refracting
Reflecting
Refracting Telescope
(Google-Images-Refracting Telescope)
This tool uses a convex lens (objective) to
collect and bend light coming from an
object.
Reflecting Telescope
( Google-Astro-canada.ca)
This tool uses a concave mirror (objective) to
collect visible light.
What is used to collect radio
waves?
The radio telescope.
Radio Telescope
(AOL- Images-Radio Telescope)
This tool collects radio waves using an antenna. One
advantage this tool has over optical telescopes is that it
can be used during the day, even if it is cloudy. The
largest telescope used on Earth is this type.
(Clip artJ0195812.wmf )
Why do astronomers use more
than one type of telescope to
observe energy/light coming
from space?

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 x-rays and gamma rays.)
How do astronomers best
detect parts of the EMS
which do not entirely
reach the surface of the
Earth?
ORBITING
SATELLITES
(AOL-Images-Telescopes)
(AOL-Images-Satellites )
What parts of the EMS are best
detected from space due to a lot
of interference from the Earth’s
atmosphere?
http:/wwwspitzer.caltech.edu/Media/guides/images/transmission.jpg
CONCLUSION:
Infrared
Ultra-Violet
X-Ray
Gamma Ray
How are they detected?
INFRARED
Using optical reflectors
with heat detectors.
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.