TelescopesTelescopes

What is the purpose of a telescope?What is the purpose of a telescope?• To gather electromagnetic radiation in To gather electromagnetic radiation in

the form of visible lightthe form of visible light. It magnifies the . It magnifies the image so “we” can see that image more image so “we” can see that image more clearly & it enlarges the image for clearly & it enlarges the image for detailed observations.detailed observations.

Refractor TelescopeRefractor Telescope

A refractor A refractor telescope uses a telescope uses a lens to gather light. lens to gather light. It has an objective It has an objective lens (convex) and lens (convex) and an eyepiece which an eyepiece which enlarges or enlarges or magnifies the magnifies the image. Light image. Light travels in straight travels in straight lines.lines.

Reflecting TelescopeReflecting Telescope

A reflecting A reflecting telescope has a telescope has a curved mirror curved mirror that that gathers light which gathers light which can be reflected to can be reflected to a smaller mirror a smaller mirror that focuses image that focuses image for the eye to see.for the eye to see.

TelescopesTelescopes

What is the main difference between What is the main difference between a refractor & reflector telescope?a refractor & reflector telescope?

Why are visible light telescopes built Why are visible light telescopes built on mountaintops in rural areas?on mountaintops in rural areas?

What prevents telescopes on Earth What prevents telescopes on Earth seeing clearly that telescopes in seeing clearly that telescopes in space not have to deal with?space not have to deal with?

Electromagnetic RadiationElectromagnetic Radiation

Electromagnetic radiation is energy Electromagnetic radiation is energy that travels through space in thethat travels through space in the form of wavesform of waves. These waves have . These waves have varying lengths. Some are long and varying lengths. Some are long and some are very short.some are very short.

Electromagnetic RadiationElectromagnetic Radiation

Electromagnetic RadiationElectromagnetic Radiation

These waves are energy. These waves are energy. (Energy is (Energy is the ability to cause changethe ability to cause change. . 2 types 2 types of energyof energy: : potential – which is stored potential – which is stored energy and kinetic – energy which is energy and kinetic – energy which is in motionin motion) The Earth receives ) The Earth receives energy from the sun in the form of energy from the sun in the form of radiation. Our eye can “see” the radiation. Our eye can “see” the middle of the electromagnetic waves middle of the electromagnetic waves which is visible light.which is visible light.

Electromagnetic RadiationElectromagnetic Radiation

A prism A prism (which is a transparent (which is a transparent object – can be glass, water or air) object – can be glass, water or air) breaks up or separates visible light breaks up or separates visible light into a band of colors. The rainbow into a band of colors. The rainbow – – redred, , orangeorange, , yellowyellow, green, green, , blue,blue, indigoindigo and and violetviolet. Or……. Or……

Roy G BivRoy G Biv These colors are called a spectrumThese colors are called a spectrum. .

The colors are separated by the The colors are separated by the length of their waves (wavelengths).length of their waves (wavelengths).

WavelengthsWavelengths

Electromagnetic WavelengthElectromagnetic Wavelength

A wavelength is the distance A wavelength is the distance between one wave peak and the next between one wave peak and the next wave peak. Red has the longest wave peak. Red has the longest wavelength and violet has the wavelength and violet has the shortest.shortest.

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WavelengthWavelength

Electromagnetic RadiationElectromagnetic Radiation

Can you Can you make up make up a mnemonic or a mnemonic or silly silly saying saying to remember the order of to remember the order of wavelengths for the electromagnetic wavelengths for the electromagnetic radiation?radiation?

From longest to shortest:From longest to shortest: Radio, microwaves, infrared, visible, Radio, microwaves, infrared, visible,

ultraviolet, x-rays & gamma raysultraviolet, x-rays & gamma rays

Types of scopesTypes of scopes

A can A can radio telescope can pick radio radio telescope can pick radio waveswaves. These waves are not affected . These waves are not affected by clouds or bad weather. These by clouds or bad weather. These telescopes can be located at low telescopes can be located at low altitudes because they pass freely altitudes because they pass freely through Earth’s atmosphere.through Earth’s atmosphere.

Spectroscope – used to break up or Spectroscope – used to break up or separate electromagnetic radiationseparate electromagnetic radiation. . Allows astronomers to “see” what Allows astronomers to “see” what type of energy an object is emitting.type of energy an object is emitting.

Types of scopesTypes of scopes

Radio waves from galaxyRadio waves from galaxy

Types of scopesTypes of scopes

X-rays from spaceX-rays from space

Types of scopesTypes of scopes

Picture of Milky Way Galaxy from Picture of Milky Way Galaxy from HubbleHubble

Types of scopesTypes of scopes

Infrared of Milky Way GalaxyInfrared of Milky Way Galaxy