AST 220 TEST 2 QUESTIONS WITH
COMPLETE ANSWERS
lens - ANSWER piece of glass or other transparent substance with curved sides for
concentrating or dispersing light rays
retina - ANSWER the light-sensitive inner surface of the eye, containing the receptor
rods and cones plus layers of neurons that begin the processing of visual information
optic nerve - ANSWER the nerve that carries neural impulses from the eye to the brain
shutter - ANSWER a device that opens and closes in front of the lens of a camera
detector - ANSWER device sensitive to electromagnetic radiation that makes a record of
astronomical observations
refraction - ANSWER light being caused to change direction
focus - ANSWER the point at which rays of light converge or appear to diverge after
passing through a lens or reflecting from a mirror
focal plane - ANSWER The plane at the focal length of a lens or concave mirror on which
an extended object is focused.
image - ANSWER a copy of an object formed by reflected or refracted rays of light
light-collecting area - ANSWER the area of the primary mirror or lens that collects light
in a telescope
angular resolution - ANSWER The ability of a telescope to distinguish between adjacent
objects in the sky.
refracting telescope - ANSWER A telescope that uses convex lenses to gather and focus
light
reflecting telescope - ANSWER A telescope that uses a curved mirror to collect and
focus light
diffraction limit - ANSWER the angular resolution that a telescope could achieve if it
were limited only by the interference of light waves
light pollution - ANSWER human-made light that hinders astronomical observations
turbulence - ANSWER high velocity winds or air currents
adaptive optics - ANSWER a technique in which telescope mirrors flex rapidly to
, compensate for the bending of starlight caused by atmospheric turbulence.
imaging - ANSWER creating a visual representation of an object or phenomenon by
scanning it with a detector or electromagnetic beam
spectroscopy - ANSWER the branch of science concerned with the investigation and
measurement of spectra produced when matter interacts with or emits electromagnetic
radiation.
gamma rays - ANSWER penetrating electromagnetic radiation of a kind arising from the
radioactive decay of atomic nuclei.
x-rays - ANSWER electromagnetic waves with wavelengths shorter than ultraviolet rays,
but longer than gamma rays
ultraviolet light - ANSWER form of radiation which is not visible to the human eye
visible light - ANSWER electromagnetic waves that are visible to the human eye
infrared light - ANSWER electromagnetic radiation with wavelengths longer than visible
light but shorter than radio waves
radio waves - ANSWER the part of the electromagnetic spectrum that consists of waves
with the lowest frequencies
what do both an eye and a camera have? - ANSWER lens
what part of a camera corresponds with the pupil? - ANSWER shutter
what part of a camera corresponds with the retina? - ANSWER charge-coupled device
why is the light collecting area important? - ANSWER it allows for objects to be seen that
are too dim to be seen with the human eye
what does angular resolution do? - ANSWER sharpens the image
what is a disadvantage of refracting telescopes? - ANSWER it can be hard to get a
perfect lens to use
what is an advantage of reflecting telescopes? - ANSWER theyre smaller and easier to
port around
what 3 things do scientists do with telescopes? - ANSWER take pictures, collect
spectra, look at variations in the intensity
why is it important to have high positions when using a telescope? - ANSWER less
atmophere to pass through
why is it important to have dry conditions when using a telescope? - ANSWER no clouds
to block your view
COMPLETE ANSWERS
lens - ANSWER piece of glass or other transparent substance with curved sides for
concentrating or dispersing light rays
retina - ANSWER the light-sensitive inner surface of the eye, containing the receptor
rods and cones plus layers of neurons that begin the processing of visual information
optic nerve - ANSWER the nerve that carries neural impulses from the eye to the brain
shutter - ANSWER a device that opens and closes in front of the lens of a camera
detector - ANSWER device sensitive to electromagnetic radiation that makes a record of
astronomical observations
refraction - ANSWER light being caused to change direction
focus - ANSWER the point at which rays of light converge or appear to diverge after
passing through a lens or reflecting from a mirror
focal plane - ANSWER The plane at the focal length of a lens or concave mirror on which
an extended object is focused.
image - ANSWER a copy of an object formed by reflected or refracted rays of light
light-collecting area - ANSWER the area of the primary mirror or lens that collects light
in a telescope
angular resolution - ANSWER The ability of a telescope to distinguish between adjacent
objects in the sky.
refracting telescope - ANSWER A telescope that uses convex lenses to gather and focus
light
reflecting telescope - ANSWER A telescope that uses a curved mirror to collect and
focus light
diffraction limit - ANSWER the angular resolution that a telescope could achieve if it
were limited only by the interference of light waves
light pollution - ANSWER human-made light that hinders astronomical observations
turbulence - ANSWER high velocity winds or air currents
adaptive optics - ANSWER a technique in which telescope mirrors flex rapidly to
, compensate for the bending of starlight caused by atmospheric turbulence.
imaging - ANSWER creating a visual representation of an object or phenomenon by
scanning it with a detector or electromagnetic beam
spectroscopy - ANSWER the branch of science concerned with the investigation and
measurement of spectra produced when matter interacts with or emits electromagnetic
radiation.
gamma rays - ANSWER penetrating electromagnetic radiation of a kind arising from the
radioactive decay of atomic nuclei.
x-rays - ANSWER electromagnetic waves with wavelengths shorter than ultraviolet rays,
but longer than gamma rays
ultraviolet light - ANSWER form of radiation which is not visible to the human eye
visible light - ANSWER electromagnetic waves that are visible to the human eye
infrared light - ANSWER electromagnetic radiation with wavelengths longer than visible
light but shorter than radio waves
radio waves - ANSWER the part of the electromagnetic spectrum that consists of waves
with the lowest frequencies
what do both an eye and a camera have? - ANSWER lens
what part of a camera corresponds with the pupil? - ANSWER shutter
what part of a camera corresponds with the retina? - ANSWER charge-coupled device
why is the light collecting area important? - ANSWER it allows for objects to be seen that
are too dim to be seen with the human eye
what does angular resolution do? - ANSWER sharpens the image
what is a disadvantage of refracting telescopes? - ANSWER it can be hard to get a
perfect lens to use
what is an advantage of reflecting telescopes? - ANSWER theyre smaller and easier to
port around
what 3 things do scientists do with telescopes? - ANSWER take pictures, collect
spectra, look at variations in the intensity
why is it important to have high positions when using a telescope? - ANSWER less
atmophere to pass through
why is it important to have dry conditions when using a telescope? - ANSWER no clouds
to block your view
