6. The refraction properties
of glass (the way it bends
light) are used to gather
parallel rays of light and
focus them to a point. The
image is created at the
focal point of the telescope.
11. A large concave mirror
(the center is thinner
than the edges) collects
and reflects the light to
make an image.
12. Reflecting telescopes can
see objects that are a
millionth or a billionth the
brightness of the faintest
star that can be seen by the
human eye alone.
18. Diagonal/
Secondary Mirror
In a reflecting telescope,
a mirror that directs the
light from the primary
mirror to a focal position.
19.
20. Cassegrain Telescope
A type of reflecting
telescope in which
incoming light hits the
primary mirror and is then
reflected upward toward
the prime focus,
21. where a secondary mirror
reflects the light back
down through a small hole
in the main mirror into a
detector or eyepiece.
22.
23. Newtonian Telescope
A reflecting telescope designed
so that the focused light is
reflected by a small secondary
mirror out to the side of the
telescope, where it can be
viewed.
24.
25. Aperture
The opening in a telescope
or other optical instrument
that determines how much
light it collects.
26. The size of the diaphragm
opening in a telescope’s lens
regulates amount of light
passes through onto the film
inside the camera the moment
when the shutter curtain in
telescope opens during an
exposure process.
27.
28.
29. Lens
An optical instrument, made
of glass or some other
transparent material, shaped
so that parallel rays of light
passing through it are bent to
arrive at a single focus.
30.
31. Filter
Color filters are usually
constructed using transparent
pieces of dyed glass, plastic,
lacquered gelatin (e.g. Wratten
filters) that have been treated to
selectively transmit the desired
wavelengths while restricting
others
38. These filters differ from
absorption filters in the
fact that they reflect and
destructively interfere with
unwanted wavelengths as
opposed to absorbing
them.
41. When you take a picture
with a digital camera, the
image is recorded by a
sensor, called a "charged
coupled device" or CCD
42.
43.
44.
45. Focal Plane
The surface where the
lenses and/or mirrors of a
telescope form an image of
a distant object.
46.
47. Focus
Also called an image
point, a point in an optical
system in which light rays
are brought together; the
location where an image
forms in such systems.
48.
49.
50. Coherent
A relationship indicating
that electromagnetic waves
are in synchronization with
each other. Waves that are
coherent exhibit persistent
interference effects.
51.
52. Chromatic Aberration
A distortion of an
optical system that results
in different colors not
focusing in the same way,
often producing color
fringes or distorted shapes.
53.
54.
55. Dispersion
The spreading of light
or other electromagnetic
radiation into a spectrum.
A rainbow is an example of
the dispersion of light
caused by raindrops.
58. Instead, they are colors
arbitrarily chosen to
represent other properties
of the body, such as the
intensity of radiation at
other than visible wave
lengths.
65. Regardless of the
brightness of the light, no
electrons are emitted
unless the photons' energy
is greater than a value that
depends on the material.
66.
67.
68. Pixel
The term "pixel" is
actually short for "Picture
Element." These small
little dots are what make
up the images on computer
displays.
69. The screen is divided up
into a matrix of thousands
or even millions of pixels.
Typically, you cannot see
the individual pixels,
because they are so small.
73. Ex: a galaxy with a high
density of stars will have a
high surface brightness,
but one with the same
number of stars more
widely spread out will have
a lower surface brightness.
