How do we know what we know about the universe? By studying the energy ( light ) emitted by objects in space.

How do we know How do we know whatwhat

we know about we know about thethe

universe? universe?

By studying the energy By studying the energy ( light ) emitted by objects ( light ) emitted by objects

in space.in space.

What do we call What do we call all the all the

energy/light we energy/light we receive from receive from

space?space? The The Electromagnetic Electromagnetic

SpectrumSpectrum

http:/www.electro-optical.com/images/em_spect.gifhttp:/www.electro-optical.com/images/em_spect.gif

What forms of energy/light What forms of energy/light can actually reach most of can actually reach most of

the Earth’s surface?the Earth’s surface?

VISIBLE LIGHTVISIBLE LIGHT RADIO WAVESRADIO WAVES

SOME ULTRAVIOLET LIGHTSOME ULTRAVIOLET LIGHT

http:/wwwspitzer.caltech.edu/Media/guides/images/http:/wwwspitzer.caltech.edu/Media/guides/images/transmission.jpgtransmission.jpg

What tools do we What tools do we use to observe these use to observe these forms of energy that forms of energy that

reach the Earth’s reach the Earth’s surface?surface?

* Telescopes** Telescopes*

What types of telescopes What types of telescopes do we use to observe do we use to observe

visible light?visible light?

Optical Telescopes:Optical Telescopes:RefractingRefracting

ReflectingReflecting

Refracting TelescopeRefracting Telescope(Google-Images-Refracting Telescope)(Google-Images-Refracting Telescope)

This tool uses a convex lens (objective) to This tool uses a convex lens (objective) to collect and bend light coming from an collect and bend light coming from an

object.object.

Reflecting TelescopeReflecting Telescope( Google-Astro-canada.ca)( Google-Astro-canada.ca)

This tool uses a concave mirror This tool uses a concave mirror (objective) to collect visible light.(objective) to collect visible light.

What is used to collect What is used to collect radio waves?radio waves?

The radio telescope.The radio telescope.

Radio TelescopeRadio Telescope

(AOL- Images-Radio Telescope)(AOL- Images-Radio Telescope)

This tool collects radio waves using an This tool collects radio waves using an antenna. One advantage this tool has over antenna. One advantage this tool has over

optical telescopes is that it can be used optical telescopes is that it can be used during the day, even if it is cloudy. The during the day, even if it is cloudy. The

largest telescope used on Earth is this type.largest telescope used on Earth is this type.

(Clip artJ0195812.wmf )(Clip artJ0195812.wmf )

Why do astronomers use Why do astronomers use more than one type of more than one type of telescope to observe telescope to observe

energy/light coming from energy/light coming from space?space?

Most telescopes are only designed to detect a Most telescopes are only designed to detect a particular portion of the Electromagnetic particular portion of the Electromagnetic Spectrum (EMS).Spectrum (EMS).

Due to the Earth’s atmosphere, not all Due to the Earth’s atmosphere, not all telescopes work best placed on the surface of telescopes work best placed on the surface of the Earth. the Earth.

( Water vapor interferes with infrared, ozone ( Water vapor interferes with infrared, ozone blocks most of the ultra-violet, the atmosphere blocks most of the ultra-violet, the atmosphere

absorbs or scatters most x-rays and gamma absorbs or scatters most x-rays and gamma rays.)rays.)

How do astronomers best How do astronomers best detect parts of the EMS detect parts of the EMS

which do not entirely which do not entirely reach the surface of the reach the surface of the

Earth?Earth?

ORBITINGORBITING SATELLITES SATELLITES

(AOL-Images-Telescopes)(AOL-Images-Telescopes)

(AOL-Images-Satellites )(AOL-Images-Satellites )

What parts of the EMS What parts of the EMS are best detected from are best detected from

space due to a lot of space due to a lot of interference from the interference from the Earth’s atmosphere?Earth’s atmosphere?

http:/wwwspitzer.caltech.edu/Media/guides/images/http:/wwwspitzer.caltech.edu/Media/guides/images/transmission.jpgtransmission.jpg

CONCLUSION:CONCLUSION: InfraredInfrared

Ultra-VioletUltra-Violet

X-RayX-Ray

Gamma RayGamma Ray

How are they How are they detected?detected?

INFRAREDINFRARED

Using optical Using optical reflectors with reflectors with heat detectors.heat detectors.

Ultra-Violet, X-Rays and Ultra-Violet, X-Rays and Gamma RaysGamma Rays

• Data is sent back from telescopes placed Data is sent back from telescopes placed in space and then sent to receivers on in space and then sent to receivers on the ground for computer analysis.the ground for computer analysis.

• Due to the high energy of X-Rays and Due to the high energy of X-Rays and Gamma Rays, they cannot be directly Gamma Rays, they cannot be directly collected since they go right through the collected since they go right through the telescopes. As a result, new technology telescopes. As a result, new technology has been developed to measure their has been developed to measure their presence indirectly.presence indirectly.