Objective
Describe the use of technology to observe objects in the Solar System
Comparing Reflecting and Refracting Telescopes
Refracting Telescopes
The purpose of a refracting
telescope is to collect and
concentrate light from distant
objects. It is made up of
lenses. Light is collected
through the lens. As light
passes through the lens, it is
refracted (this means the light
is bent).
The refractor has two lenses. The first is the primary lens. This is located in the front
of the telescope. The light is refracted until it hits the second lens – the eyepiece lens.
This is where you look to see the object at which your telescope is pointed.
The light waves travel parallel to each other until they hit the primary lens. The
primary lens than refracts the light back to the eyepiece. The light is refracted to the
eyepiece and the eyepiece is used to focus the image (make it sharp).
A problem with refractors is chromatic aberration. (If you look at an image through a
refractor’s eyepiece and see a rainbow around the edges of an object, you are
experiencing chromatic aberration.) Using the proper lenses will make sure the light
waves refract to the same point.
All refracting telescopes are basically the same.
Reflector Telescopes
A reflector uses mirrors to produce and image in the eyepiece. The mirror reflects the
light to a secondary mirror. The secondary mirror reflects into the eyepiece. The
eyepiece is used to focus the image (make it sharp).
Objective
Describe the use of technology to observe objects in the Solar System
Sir Isaac Newton made the first
reflector. It is traditionally called
the Newtonian Reflector.
The primary mirror collects and
concentrates light from distant
objects. The parallel light waves
reflect off the mirror to the
secondary mirror. The secondary
mirror reflects the light into the
lens of the eyepiece. The light is refracted through the lens in the eyepiece where you
look to see the image.
Because the reflector uses mirrors, you don’t have a problem with chromatic
aberration like the one you do with refractors. Images are sharp and clear.
There are many different types of reflecting telescopes. The key difference between
the different designs is the location of the secondary mirror.
Cassegrain Reflector
Schmidt-Cassegrain Reflector
With this information, complete the graphic organizer.
Objective
Describe the use of technology to observe objects in the Solar System
Name _____________________________________________________________
Comparing Reflecting and Refracting Telescopes
Read the information about reflecting and refracting telescopes and complete the
graphic organizer.
Reflecting Telescopes
Refracting Telescopes
Uses lenses or mirrors?
Uses lenses or mirrors?
What part of telescope collects
light?
What part of telescope collects
light?
How is image formed?
How is image formed?
Does chromatic aberration occur
(yes or no)?
Does chromatic aberration occur
(yes or no)?
Types?
Types?
Objective
Describe the use of technology to observe objects in the Solar System
Comparing Reflecting and Refracting Telescopes - Key
Refracting Telescopes
Reflecting Telescopes
Uses lenses or mirrors?
Uses lenses or mirrors?
Mirrors
Lenses
What part of telescope collects light?
What part of telescope collects light?
The mirror
The lenses
How is image formed?
How is image formed?
Example: Light hits mirror,
bounces to secondary mirror,
eyepiece focuses image.
Example: Light is bent
(refracted) as it goes through
lens. Eyepiece focuses image.
Does chromatic aberration occur (yes or
no)?
Does chromatic aberration occur (yes or
no)?
No
Yes
Types?
Types?
Example: There are many
Example: All refracting
different types of reflecting
telescopes are basically the
telescopes. The key difference same.
between the different designs
is the location of the secondary
mirror.