Transcript Notes - Rudds Classroom

The Solar
System:
A6: Telescopes
The Telescope
• Telescope – device that makes distant object
appear closer
– A Dutch lens maker, Hans Lippershey,
invented the telescope in 1608
– Galileo made it famous in 1610
when he used it to see objects
in the night sky
– Galileo was the first person
to ever see sun spots,
Saturn’s rings, and the large
moons of Jupiter
Electromagnetic Radiation
• To understand how a telescope works, it is useful
to understand the nature of electromagnetic
radiation
– Forms of Radiation – energy that travels
through space in waves
– Visible Light – Light that can be seen is one
type of electromagnetic radiation
– Other types of radiation include: radio
waves, x-rays, gamma rays, and more
Electromagnetic Radiation
– Electromagnetic Spectrum – includes the
entire range of visible and non-visible waves
– Recall, a wave length is the distance from the
crest of one wave to the crest of the next
– Also recall that wave lengths increase
towards the red end of the spectrum
Draw in your
notes
In which
direction does
the energy
increase?
Types of Telescopes
• Optical Telescopes – use lenses or mirrors to
collect and focus light making objects appear
larger and brighter
– Refracting Telescope – uses convex lenses
– Convex Lens – clear glass curved so that the
middle is thicker than the edges
– A simple refracting
telescope, like the one
Galileo used, has two
convex lenses at the
ends of a long tube
Types of Telescopes
– Light enters through the larger objective lens
– The objective lens focuses the light a certain
distance from the lens
– That distance is the focal length of the lens
– The smaller lens is the eyepiece
– The eyepiece lens
magnifies the
image produced
by the objective
lens
Types of Telescopes
– Reflecting Telescope – uses a curved mirror to
collect and focus light
– Invented in 1668 by Isaac Newton
– Instead of an objective lens, the mirror
focuses the light
– They can be made much bigger
– Less optical irregularities
and brighter images
– All the largest
telescopes today
are reflecting
Other Types of Telescopes
• Other Types of Telescopes – collect and focus
different types of electromagnetic radiation
(instead of visible light)
– Radio Telescope – Curved, reflecting surfaces
used to detect radio waves.
– Surface reflects and concentrates radio
waves like a mirror in a refracting scope
– The concentrated waves are
projected onto a small antenna
– The larger the curved surface is,
the more waves it can collect
Other Telescopes
– Infrared Telescope – Use infrared
light to detect celestial bodies
– They contain a camera and a special solidstate infrared detector which must be cooled
to cryogenic temperatures
– Can be ground-based, air-based, or in space
– Because water vapors in the air
absorb infrared, ground-based
scopes are usually on mountains
in very dry climates
– Putting them in space eliminates
the atmosphere’s interference
Other Types of Telescopes
– Other Telescope – Other types of telescopes
include ultraviolet, x-ray, and gamma ray scopes
– To understand how the images of the
telescopes differ, below are pictures of the
Crab Nebula taken with each.
Video
In Closing
• Why do you think telescopes were first
invented?
• Why are telescopes important to the study of
astronomy?