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Telescopes
1.
2.
They can collect far more light than the unaided eye
They can magnify very small images
Different Types of Optical Telescopes
(uses lenses and mirrors to gather and focus starlight)
1. refracting telescope – bends or refracts starlight through
the first lens to focus the image through the second lens (the
eye piece)
2. reflecting telescope – uses one large curved mirror to
focus starlight
3. multiple-mirror telescopes – many reflecting mirrors
working in unison to produce larger, higher resolution images
Refracting Telescope
Reflecting Telescope
Mt Palomar 200" Reflecting Telescope
Multiple-Mirror Telescope Observatory in Mt. Hopkins, Arizona
Telescopes (cont.)
Famous Telescopes
Schmidt Telescope – uses
both reflecting mirrors
and refracting lenses
Telescopes (cont.)
Famous 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 Telescopes
Spectroscope – uses a prism to separate visible light and
determine the chemical composition of a 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-up
radio waves emitted by quasars and pulsars
Arecibo in Puerto Rico (1000’ dia.)
The Very Large Array (VLA) in
San Agustin, NM
→→→→→
Electromagnetic Spectrum
The elecromagnetic
spectrum includes
all forms of radiation,
7% of which is visible
light -- the radiation
to which our eyes
are sensitive.
 The spectrum
up according to
the wavelength
of the radiation.

Electromagnetic Spectrum
Doppler Effect
The apparent change
in the wavelength
due to an object's
motion
Sound: like the
whistle on a train or
a car horn as it goes
past.
Doppler Effect
Red shift – as an object moves
away – the wavelength the star
radiates gets longer… toward
the RED end of the spectrum
 The faster the distance
increases the greater the
‘Red Shift’
The object is moving away from
us
Doppler Effect
Blue shift – as an object moves toward –
the wavelength the star radiates gets
shorter… toward the BLUE end of the
spectrum
 The faster the distance decreases the
greater the
‘Blue Shift’
The object is moving toward US
Parallax
the apparent
displacement of
an observed
object due to a
change in the
position of the
observer
http://sci2.esa.int/interactive/media/flashes/2_1_1.htm
Parallax
http://sci2.esa.int/interactive/media/flashes/2_1_1.htm