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Telescopes
Telescopes
Key Concepts
 What are the regions of the
electromagnetic spectrum?
 What are telescopes and how do they
work?
 Where are most large telescopes
located?
Telescopes - Key Terms
 Telescope
 Refracting
 Electromagnetic
telescope
 Convex lens
 Reflecting
telescope
 Radio telescope
 Observatory
radiation
 Visible light
 Wavelength
 Spectrum
 Optical
telescope
Telescope
A device that makes distant objects
appear to be closer.
 Galileo made the telescope famous.
He was the first to see sunspots,
Saturn’s Rings, and the four large
moons of Jupiter

Electromagnetic Radiation
Energy that can travel through space in
the form of waves
Examples of Forms of Radiation

visible light – radiation you can see
 infrared – feel as heat
 radio waves

Ranges from long wavelength radio waves to
short wavelength gamma rays
Types of Telescopes
Instruments that collect and focus
light and other forms of electromagnetic
radiation.
 Optical telescope – uses lenses or
mirrors to collect and focus visible light

 Two types – refracting and reflecting

Non-optical – Use other forms of
electromagnetic radiation such as radio
waves, x-rays and gamma rays
Refracting Telescopes





Uses convex lenses to gather and focus
light
Convex lens is a curved piece of glass that
is thicker in the middle than the edges
The larger the lens the more light the
telescope can collect
Simple refracting telescope has 2
lenses – the objective lens and the
eyepiece lens
Yerkes Telescope in Wisconsin is the
largest refracting telescope
Reflecting Telescopes
Isaac Newton built the first in 1668
 Uses a curved mirror to collect and focus
light
 The larger the mirror, the more light that
can be collected
 Largest optical telescopes today are
reflecting

Radio Telescopes
Devices used to detect radio
waves from objects in space
 Most have curved reflecting surfaces
that focus radio waves the way the
mirror does in reflecting telescopes
 Concentrate the faint radio
signals onto small antennas like
those on radios
Ex. The Very large Array, Arecibo

Other Telescopes
Detect:
 Infrared – Spitzer Space Telescope
 Ultraviolet
 X-rays – Chandra X-Ray Observatory
 Gamma rays
Hubble Space Telescope detects
visible, ultraviolet, and infrared
Observatories
A building that contains one or more
telescopes. (some in space)
 Many large observatories located on
mountaintops or in space – atmosphere
makes images blurry.
 Radio telescopes are not affected by
atmosphere
