Question 1

Explain the difference between dispersion and diffraction.How can both phenomena be used to create a spectrum?

Accepted Answer

Dispersion is the wavelength dependence

Question 2

What part(s) of the human eye is responsible for detecting light?

Accepted Answer

A)  cornea 
B)  lens 
C)  pupil 
D)  rods and cones 
E)  iris 
A)  cornea 
B)  lens 
C)  pupil 
D)  rods and cones 
E)  iris

Question 3

Why do astronomers need to study microwaves, instead of visible light, in order to understand the Big Bang?

Accepted Answer

The energy left over from the Big Bang g

Question 4

You hear a news story about an X-ray telescope being built on Earth.You know this can't be possible because

Accepted Answer

A)  X-rays do not travel very far through Earth's atmosphere. 
B)  X-ray telescopes are impossible to build. 
C)  X-ray telescopes would receive too much interference from hospitals. 
D)  it would cost too much money. 
E)  X-rays see through things, making them pointless for observations. 
A)  X-rays do not travel very far through Earth's atmosphere. 
B)  X-ray telescopes are impossible to build. 
C)  X-ray telescopes would receive too much interference from hospitals. 
D)  it would cost too much money. 
E)  X-rays see through things, making them pointless for observations.

Question 5

Particle accelerators that smash atoms or particles together at high speeds, such as the Large Hadron Collider (LHC), are important tools used for simulating conditions in

Accepted Answer

A)  the early universe. 
B)  the solar wind. 
C)  red giants. 
D)  brown dwarf stars. 
E)  planetary nebula. 
A)  the early universe. 
B)  the solar wind. 
C)  red giants. 
D)  brown dwarf stars. 
E)  planetary nebula.

Question 6

NASA's Kuiper Airborne Observatory and the Stratospheric Observatory for Infrared Astronomy (SOFIA) are two examples of telescopes placed in high-flying aircraft.Why would astronomers put telescopes in airplanes?

Accepted Answer

A)  to get the telescopes closer to the stars 
B)  to get the telescopes away from the light pollution of cities 
C)  to get the telescopes above the majority of the water vapor in Earth's atmosphere 
D)  to be able to observe one object for more than 24 hours without stopping 
E)  to allow the telescopes to observe the full spectrum of light 
A)  to get the telescopes closer to the stars 
B)  to get the telescopes away from the light pollution of cities 
C)  to get the telescopes above the majority of the water vapor in Earth's atmosphere 
D)  to be able to observe one object for more than 24 hours without stopping 
E)  to allow the telescopes to observe the full spectrum of light

Question 7

What property of light allows a grating to disperse the light from an object into a spectrum?

Accepted Answer

A)  interference 
B)  reflection 
C)  refraction 
D)  aberration 
E)  magnification 
A)  interference 
B)  reflection 
C)  refraction 
D)  aberration 
E)  magnification

Question 8

Why is it difficult to view low-surface-brightness objects, such as the Andromeda Galaxy, with the naked eye? Does the view improve with the use of a telescope? What is needed to get a bright, clear view of the Andromeda Galaxy, as commonly seen in pictures?

Accepted Answer

The human eye has a low integration time

Question 9

Why don't astronomers put all telescopes in space?

Accepted Answer

Building and launching a telescope into

Question 10

The image of a star in the figure below does not look like a single dot due to

Accepted Answer

A)  refraction. 
B)  chromatic aberration. 
C)  spectral dispersion. 
D)  segmented mirrors. 
E)  diffraction. 
A)  refraction. 
B)  chromatic aberration. 
C)  spectral dispersion. 
D)  segmented mirrors. 
E)  diffraction.

Question 11

Typically, video is shot using 24-30 frames per second (one frame each 33-42 ms).If a filmmaker shot new experimental video at 100 frames per second (one frame each 10 ms), how would it look during playback to the human eye if played at 100 frames per second?

Accepted Answer

A)  It would look like the video was being fast-forwarded. 
B)  It would look like the video was about the same as normal video. 
C)  It would look like the video was being played back in slow motion. 
D)  It would look like a slideshow, a series of pictures on the screen each for a perceptible amount of time. 
E)  It would look like the video was about the same speed as normal video, but blurry. 
A)  It would look like the video was being fast-forwarded. 
B)  It would look like the video was about the same as normal video. 
C)  It would look like the video was being played back in slow motion. 
D)  It would look like a slideshow, a series of pictures on the screen each for a perceptible amount of time. 
E)  It would look like the video was about the same speed as normal video, but blurry.

Question 12

A spectrograph is

Accepted Answer

A)  a device used for clearly resolving physical details of distant objects. 
B)  typically made from two ordinary pieces of glass. 
C)  a device used to measure the intensity of light at each wavelength. 
D)  a radio telescope. 
E)  a visible-light telescope. 
A)  a device used for clearly resolving physical details of distant objects. 
B)  typically made from two ordinary pieces of glass. 
C)  a device used to measure the intensity of light at each wavelength. 
D)  a radio telescope. 
E)  a visible-light telescope.

Question 13

Explain how adaptive optics help compensate for atmospheric seeing.

Accepted Answer

Slight perturbances in the atmosphere ca

Question 14

What optical phenomenon is pictured in the figure below?

Accepted Answer

A)  reflection 
B)  refraction 
C)  diffraction 
D)  interference 
E)  chromatic aberration 
A)  reflection 
B)  refraction 
C)  diffraction 
D)  interference 
E)  chromatic aberration

Question 15

What are gravitational waves, and how are they detected?

Accepted Answer

Gravitational waves are waves in the for

Question 16

Grote Reber conducted the first radio survey of the sky in the 1930s and 1940s with his 9-m-diameter radio telescope.Why did his telescope need to be so large?

Accepted Answer

A)  He needed a large light-collecting area because radio sources are notoriously dim. 
B)  He needed better angular resolution to identify sources because radio waves are so long. 
C)  He needed a higher magnification to identify sources because radio sources are quite small. 
D)  He needed a longer focal length because radio sources are so far away. 
E)  He needed a shorter focal length because radio sources are so far away. 
A)  He needed a large light-collecting area because radio sources are notoriously dim. 
B)  He needed better angular resolution to identify sources because radio waves are so long. 
C)  He needed a higher magnification to identify sources because radio sources are quite small. 
D)  He needed a longer focal length because radio sources are so far away. 
E)  He needed a shorter focal length because radio sources are so far away.

Question 17

As a beam of light travels from one medium to another, the change in direction of the beam of light depends on

Accepted Answer

A)  the wavelength of the light. 
B)  the index of refraction of the outgoing medium. 
C)  the index of refraction of the incoming medium. 
D)  the angle of incidence. 
E)  all of these 
A)  the wavelength of the light. 
B)  the index of refraction of the outgoing medium. 
C)  the index of refraction of the incoming medium. 
D)  the angle of incidence. 
E)  all of these

Question 18

Why do astronomers use monochromatic CCDs instead of color CCDs like your cell phone does?

Accepted Answer

A)  Color CCDs have worse angular resolution. 
B)  They don't make color CCDs large enough. 
C)  Monochromatic CCDs last longer. 
D)  Monochromatic CCDs have smaller angular resolution. 
E)  Color CCDs can't detect infrared light. 
A)  Color CCDs have worse angular resolution. 
B)  They don't make color CCDs large enough. 
C)  Monochromatic CCDs last longer. 
D)  Monochromatic CCDs have smaller angular resolution. 
E)  Color CCDs can't detect infrared light.

Question 19

The angular resolution of the largest single-dish radio telescope in the United States, the 100-m Green Bank Telescope, is ________ when it operates at a wavelength of 20 cm.

Accepted Answer

A)  41 arcmin 
B)  6.9 arcmin 
C)  4.1 arcmin 
D)  6.9 arcsec 
E)  4.1 arcsec 
A)  41 arcmin 
B)  6.9 arcmin 
C)  4.1 arcmin 
D)  6.9 arcsec 
E)  4.1 arcsec

Question 20

Before charge-coupled devices (CCDs) were invented, what was the device most commonly used for imaging with optical telescopes?

Accepted Answer

A)  Polaroid cameras 
B)  photographic glass plates 
C)  35-mm film 
D)  high-speed film 
E)  video cameras 
A)  Polaroid cameras 
B)  photographic glass plates 
C)  35-mm film 
D)  high-speed film 
E)  video cameras

Exam 6: The Tools of the Astronomer

Explain the difference between dispersion and diffraction.How can both phenomena be used to create a spectrum?

What part(s) of the human eye is responsible for detecting light?

Why do astronomers need to study microwaves, instead of visible light, in order to understand the Big Bang?

You hear a news story about an X-ray telescope being built on Earth.You know this can't be possible because

Particle accelerators that smash atoms or particles together at high speeds, such as the Large Hadron Collider (LHC), are important tools used for simulating conditions in

NASA's Kuiper Airborne Observatory and the Stratospheric Observatory for Infrared Astronomy (SOFIA) are two examples of telescopes placed in high-flying aircraft.Why would astronomers put telescopes in airplanes?

What property of light allows a grating to disperse the light from an object into a spectrum?

Why is it difficult to view low-surface-brightness objects, such as the Andromeda Galaxy, with the naked eye? Does the view improve with the use of a telescope? What is needed to get a bright, clear view of the Andromeda Galaxy, as commonly seen in pictures?

Why don't astronomers put all telescopes in space?

The image of a star in the figure below does not look like a single dot due to

Typically, video is shot using 24-30 frames per second (one frame each 33-42 ms).If a filmmaker shot new experimental video at 100 frames per second (one frame each 10 ms), how would it look during playback to the human eye if played at 100 frames per second?

A spectrograph is

Explain how adaptive optics help compensate for atmospheric seeing.

What optical phenomenon is pictured in the figure below?

What are gravitational waves, and how are they detected?

Grote Reber conducted the first radio survey of the sky in the 1930s and 1940s with his 9-m-diameter radio telescope.Why did his telescope need to be so large?

As a beam of light travels from one medium to another, the change in direction of the beam of light depends on

Why do astronomers use monochromatic CCDs instead of color CCDs like your cell phone does?

The angular resolution of the largest single-dish radio telescope in the United States, the 100-m Green Bank Telescope, is ________ when it operates at a wavelength of 20 cm.

Before charge-coupled devices (CCDs) were invented, what was the device most commonly used for imaging with optical telescopes?

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Cosmology

Large-Scale Structure in the Universe

Life

Filters