TelescopesTelescopes1.1. They can collect far more light than the unaided eyeThey can collect far more light than the unaided eye

2.2. They can magnify very small imagesThey can magnify very small images

Different Types of Optical TelescopesDifferent Types of Optical Telescopes

((uses lenses and mirrors to gather and focus starlight)uses lenses and mirrors to gather and focus starlight)

1. refracting telescope – bends or refracts starlight 1. refracting telescope – bends or refracts starlight through the first lens to focus the image through the through the first lens to focus the image through the second lens (the eye piece)second lens (the eye piece)

2. reflecting telescope – uses one large curved mirror 2. reflecting telescope – uses one large curved mirror to focus starlightto focus starlight

3. multiple-mirror telescopes – many reflecting 3. multiple-mirror telescopes – many reflecting mirrors working in unison to produce larger, higher mirrors working in unison to produce larger, higher resolution imagesresolution images

Refracting Telescope

Reflecting Telescope

Mt Palomar 200" Reflecting Telescope

Multiple-Mirror Telescope Observatory in Mt. Hopkins, Arizona

Telescopes (cont.)Telescopes (cont.)Famous TelescopesFamous Telescopes

Schmidt Telescope – uses Schmidt Telescope – uses both reflecting mirrors both reflecting mirrors and refracting lensesand refracting lenses

Telescopes (cont.)Telescopes (cont.)Famous TelescopesFamous Telescopes

Hubble Telescope – reflecting telescope orbiting Earth, has unparalleled resolution and usable for ultraviolet detection that is not possible from Earth’s surface

Other Types of Other Types of TelescopesTelescopes

Spectroscope – uses a prism to separate visible Spectroscope – uses a prism to separate visible light and determine the chemical composition of light and determine the chemical composition of a stara star

E.W. Maunder (at the eyepiece) and W. Bowyer observing with the half-prism spectroscope, c. 1894

Radio Telescope – very large telescope that picks-Radio Telescope – very large telescope that picks-up radio waves emitted by quasars and pulsarsup radio waves emitted by quasars and pulsars

The Very Large Array (VLA) in San Agustin, NM →→→→→

Arecibo in Puerto Rico (1000’ dia.)

Electromagnetic SpectrumElectromagnetic Spectrum The elecromagneticThe elecromagnetic spectrum includes spectrum includes all forms of radiation,all forms of radiation, 7% of which is 7% of which is visiblevisible light light -- the radiation -- the radiation to which our eyes to which our eyes are sensitive. are sensitive. The spectrum The spectrum up according toup according to the wavelength the wavelength of the radiation.of the radiation.

Electromagnetic SpectrumElectromagnetic Spectrum

Doppler EffectDoppler Effect

The apparent change The apparent change in the wavelength in the wavelength due to an object's due to an object's motionmotion

Sound: like the Sound: like the whistle on a train or whistle on a train or a car horn as it goes a car horn as it goes past.past.

Doppler EffectDoppler EffectRed shiftRed shift – as an object moves – as an object moves awayaway – the wavelength the star – the wavelength the star radiates gets radiates gets longerlonger… toward … toward the RED end of the spectrumthe RED end of the spectrum

The faster the distance The faster the distance increases the greater theincreases the greater the

‘ ‘Red Shift’Red Shift’

The object is moving The object is moving awayaway from from usus

Doppler EffectDoppler Effect

Blue shiftBlue shift – as an object moves – as an object moves towardtoward – – the wavelength the star radiates gets the wavelength the star radiates gets shortershorter… toward the BLUE end of the … toward the BLUE end of the spectrumspectrum

The faster the distance decreases the The faster the distance decreases the greater thegreater the

‘ ‘Blue Shift’Blue Shift’

The object is moving The object is moving towardtoward US US

ParallaxParallax

the apparent the apparent displacement of displacement of an observed an observed object due to a object due to a change in the change in the position of the position of the observer observer

http://sci2.esa.int/interactive/media/flashes/2_1_1.htm

ParallaxParallax

http://sci2.esa.int/interactive/media/flashes/2_1_1.htm