Question 1

For which of the following spectral ranges is it essential that astronomical observations be made from space?

Accepted Answer

A) visible 
B) far UV 
C) radio 
D) near infrared 
A) visible 
B) far UV 
C) radio 
D) near infrared

Question 2

A refracting telescope has an objective lens of focal length 80 cm, a diameter of 10 cm, and an eyepiece of focal length 5 cm and diameter 1 cm. What is the magnifying power of this telescope?

Accepted Answer

A) 10× 
B) 8× 
C) 16× 
D) 80× 
A) 10× 
B) 8× 
C) 16× 
D) 80×

Question 3

Chandra, XMM-Newton, and NuSTAR are all orbiting telescopes designed to observe primarily in which part of the spectrum?

Accepted Answer

A) infrared 
B) visible 
C) x ray 
D) gamma ray 
A) infrared 
B) visible 
C) x ray 
D) gamma ray

Question 4

One important fact to keep in mind when comparing visible and infrared images of Saturn is that:

Accepted Answer

A) neither visible nor IR is emitted by Saturn. What we see is entirely reflected from the Sun. 
B) visible radiation is emitted by Saturn but the IR is entirely reflected from the Sun. 
C) IR radiation is emitted by Saturn but the visible is entirely reflected from the Sun. 
D) both visible and IR are emitted by Saturn in substantial amounts. 
A) neither visible nor IR is emitted by Saturn. What we see is entirely reflected from the Sun. 
B) visible radiation is emitted by Saturn but the IR is entirely reflected from the Sun. 
C) IR radiation is emitted by Saturn but the visible is entirely reflected from the Sun. 
D) both visible and IR are emitted by Saturn in substantial amounts.

Question 5

A high mountaintop such as Mauna Kea in Hawaii is a good site for an infrared observatory because it is:

Accepted Answer

A) above most of the moisture in Earth's atmosphere. 
B) farther from city lights. 
C) closer to the stratospheric ozone layer. 
D) above most of the turbulence in Earth's atmosphere. 
A) above most of the moisture in Earth's atmosphere. 
B) farther from city lights. 
C) closer to the stratospheric ozone layer. 
D) above most of the turbulence in Earth's atmosphere.

Question 6

In the x-ray view of the universe (see Figure 6-32 of Universe, 11th ed.), in the wavelength range of 0.1 to 10 nm, the brightest most intense radiation comes from:
​
  ​

Accepted Answer

A) individual hydrogen atoms in interstellar space. 
B) dust particles in the plane of the Milky Way. 
C) supernova remnants. 
D) distant galaxies. 
A) individual hydrogen atoms in interstellar space. 
B) dust particles in the plane of the Milky Way. 
C) supernova remnants. 
D) distant galaxies.

Question 7

Refraction of light at a surface between two transparent substances occurs because:

Accepted Answer

A) the speed of light is different in the two materials. 
B) some light is reflected at the surface. 
C) the amount of absorption of the light changes at the surface. 
D) the frequency of the light changes at the surface. 
A) the speed of light is different in the two materials. 
B) some light is reflected at the surface. 
C) the amount of absorption of the light changes at the surface. 
D) the frequency of the light changes at the surface.

Question 8

Why is the angular resolution of a 20-m-diameter radio telescope worse than that of a 0.5-m-diameter optical telescope?

Accepted Answer

A) The ratio of wavelength to telescope diameter is larger for the radio telescope. 
B) It is difficult to make a radio dish sufficiently smooth to reflect radio waves. 
C) Atmospheric turbulence disturbs radio waves more than it does visible light. 
D) The ratio of wavelength to telescope diameter is smaller for the radio telescope. 
A) The ratio of wavelength to telescope diameter is larger for the radio telescope. 
B) It is difficult to make a radio dish sufficiently smooth to reflect radio waves. 
C) Atmospheric turbulence disturbs radio waves more than it does visible light. 
D) The ratio of wavelength to telescope diameter is smaller for the radio telescope.

Question 9

ROSAT was launched into Earth orbit in 1990 to study the universe using:

Accepted Answer

A) UV radiation. 
B) x rays. 
C) infrared. 
D) visible light. 
A) UV radiation. 
B) x rays. 
C) infrared. 
D) visible light.

Question 10

When used for photography, which of the following simple telescopes (with film or detector placed at the appropriate focus) will suffer from chromatic aberration?

Accepted Answer

A) refracting 
B) Newtonian reflecting 
C) reflecting, prime focus 
D) Cassegrain reflecting 
A) refracting 
B) Newtonian reflecting 
C) reflecting, prime focus 
D) Cassegrain reflecting

Question 11

When making a spectrum of a distant galaxy, it is usual practice to allow light from a laboratory sample of some element, say neon, to fall upon the spectrum as well. Why is this done?

Accepted Answer

A) The known positions of the neon spectrum lines allow the spectrum to be calibrated so that the wavelengths of the lines from the galaxy can be determined. 
B) The emission lines from the laboratory neon will fill in the absorption lines from neon in our atmosphere, thus getting rid of these lines so that they are not confused with lines from the galaxy. 
C) The laboratory neon lines show the maximum velocity position of neon. These laboratory neon lines can then be compared with neon lines from the galaxy spectrum so the Doppler shift based on neon can be calculated. 
D) The procedure is just a test to assure that the system is working properly without distortion before the galaxy spectrum is analyzed. 
A) The known positions of the neon spectrum lines allow the spectrum to be calibrated so that the wavelengths of the lines from the galaxy can be determined. 
B) The emission lines from the laboratory neon will fill in the absorption lines from neon in our atmosphere, thus getting rid of these lines so that they are not confused with lines from the galaxy. 
C) The laboratory neon lines show the maximum velocity position of neon. These laboratory neon lines can then be compared with neon lines from the galaxy spectrum so the Doppler shift based on neon can be calculated. 
D) The procedure is just a test to assure that the system is working properly without distortion before the galaxy spectrum is analyzed.

Question 12

At the present time (2018), the largest optical telescope in the world has a primary mirror with a diameter of about:

Accepted Answer

A) 6.0 m. 
B) 11.0 m. 
C) 30.0 m. 
D) 6.5 m. 
A) 6.0 m. 
B) 11.0 m. 
C) 30.0 m. 
D) 6.5 m.

Question 13

In a spectrograph, a glass prism has a number of disadvantages compared to a diffraction grating. Which of the following is not one of these disadvantages?

Accepted Answer

A) A prism cannot be used with a CCD detector and a computer. 
B) A prism is opaque to ultraviolet light. 
C) A prism reduces the light intensity unevenly over the spectrum. 
D) A prism does not disperse the colors uniformly. 
A) A prism cannot be used with a CCD detector and a computer. 
B) A prism is opaque to ultraviolet light. 
C) A prism reduces the light intensity unevenly over the spectrum. 
D) A prism does not disperse the colors uniformly.

Question 14

In order to correct for spherical aberration:

Accepted Answer

A) a spherical mirror is used with a correcting lens. 
B) a parabolic mirror is used with a correcting lens. 
C) an elliptical mirror is used without a correcting lens. 
D) an elliptical mirror is used with a correcting lens. 
A) a spherical mirror is used with a correcting lens. 
B) a parabolic mirror is used with a correcting lens. 
C) an elliptical mirror is used without a correcting lens. 
D) an elliptical mirror is used with a correcting lens.

Question 15

One major difference between radio waves and light is that:

Accepted Answer

A) radio waves have shorter wavelengths. 
B) radio waves are electromagnetic, unlike light. 
C) light waves are electromagnetic, unlike radio waves. 
D) radio waves have lower frequencies. 
A) radio waves have shorter wavelengths. 
B) radio waves are electromagnetic, unlike light. 
C) light waves are electromagnetic, unlike radio waves. 
D) radio waves have lower frequencies.

Question 16

The diffraction-limited angular resolution of one telescope is 0.1 arcsec and that of another is 0.2 arcsec. What does this mean?

Accepted Answer

A) The telescope with 0.1 arcsec has better resolution. 
B) The telescope with 0.2 arcsec has better resolution. 
C) It really doesn't mean anything, because telescopes are never limited by diffraction. 
D) It is relatively unimportant, because angular resolution is only one of many forms of resolution that must be taken into account. 
A) The telescope with 0.1 arcsec has better resolution. 
B) The telescope with 0.2 arcsec has better resolution. 
C) It really doesn't mean anything, because telescopes are never limited by diffraction. 
D) It is relatively unimportant, because angular resolution is only one of many forms of resolution that must be taken into account.

Question 17

The quality of images produced by a large radio telescope is limited mostly by:

Accepted Answer

A) atmospheric distortion. 
B) light pollution. 
C) diffraction. 
D) cloud cover. 
A) atmospheric distortion. 
B) light pollution. 
C) diffraction. 
D) cloud cover.

Exam 6: Optics and Telescopes

For which of the following spectral ranges is it essential that astronomical observations be made from space?

A refracting telescope has an objective lens of focal length 80 cm, a diameter of 10 cm, and an eyepiece of focal length 5 cm and diameter 1 cm. What is the magnifying power of this telescope?

Chandra, XMM-Newton, and NuSTAR are all orbiting telescopes designed to observe primarily in which part of the spectrum?

One important fact to keep in mind when comparing visible and infrared images of Saturn is that:

A high mountaintop such as Mauna Kea in Hawaii is a good site for an infrared observatory because it is:

In the x-ray view of the universe (see Figure 6-32 of Universe, 11th ed.), in the wavelength range of 0.1 to 10 nm, the brightest most intense radiation comes from: ​ ​

Refraction of light at a surface between two transparent substances occurs because:

Why is the angular resolution of a 20-m-diameter radio telescope worse than that of a 0.5-m-diameter optical telescope?

ROSAT was launched into Earth orbit in 1990 to study the universe using:

When used for photography, which of the following simple telescopes (with film or detector placed at the appropriate focus) will suffer from chromatic aberration?

When making a spectrum of a distant galaxy, it is usual practice to allow light from a laboratory sample of some element, say neon, to fall upon the spectrum as well. Why is this done?

At the present time (2018), the largest optical telescope in the world has a primary mirror with a diameter of about:

In a spectrograph, a glass prism has a number of disadvantages compared to a diffraction grating. Which of the following is not one of these disadvantages?

In order to correct for spherical aberration:

One major difference between radio waves and light is that:

The diffraction-limited angular resolution of one telescope is 0.1 arcsec and that of another is 0.2 arcsec. What does this mean?

The quality of images produced by a large radio telescope is limited mostly by:

Astronomy and the Universe

Knowing the Heavens

Eclipses and the Motion of the Moon

Gravitation and the Waltz of the Planets

The Nature of Light

Comparative Planetology I: Our Solar System

Comparative Planetology II: the Origin of Our Solar System

The Living Earth

Our Barren Moon

Mercury, Venus, and Mars: Terrestrial, yet Unique

Jupiter and Saturn: Lords of the Planets

Jupiter and Saturns Satellites of Fire and Ice

Uranus, Neptune, Pluto, and the Kuiper Belt: Remote Worlds

Asteroids, Comets, and Impacts

Our Star, the Sun

The Nature of the Stars

The Birth of Stars

Stellar Evolution: on and After the Main Sequence

Stellar Evolution: The Death of Stars

Stellar Remnants: Neutron Stars and Black Holes

Our Galaxy

Galaxies

Quasars and Active Galaxies

Cosmology: The Origin and Evolution of the Universe

Exploring the Early Universe

The Search for Extraterrestrial Life

Filters

In the x-ray view of the universe (see Figure 6-32 of Universe, 11th ed.), in the wavelength range of 0.1 to 10 nm, the brightest most intense radiation comes from: