According to the classification system in Ch. 1, the concept of dark matter is classified as:

According to the classification system in Ch. 1, the concept of dark matter is classified as:

a) an idea
b) a theory
c) a law
d) a principle

Answer: B

The Helium abundance in the current universe

The Helium abundance in the current universe

a) is due partly to the Big Bang and partly to stellar nucleosynthesis
b) is due only to the Big Bang
c) is due only to stellar evolution
d) is unknown at large scales

Answer: A

T/F The universe became transparent when it cooled below the surface temperature of the sun.

T/F The universe became transparent when it cooled below the surface temperature of the sun.

Answer: True

The cosmological redshift in Hubble's law is distinct from the redshift arising from the Doppler effect because

The cosmological redshift in Hubble's law is distinct from the redshift arising from the Doppler effect because

a) the redshift happens as the photon moves through expanding space
b) the redshift happens as the galaxy moves through space
c) it is used for the light, not for sound
d) the two are not distinct, they are the same

Answer: A

T/F The cosmological constant makes the expansion of the universe accelerate.

T/F The cosmological constant makes the expansion of the universe accelerate.

Answer: True

Which of the following adjectives describes the early universe, as observed through the CMB?

Which of the following adjectives describes the early universe, as observed through the CMB?

a) hot
b) dense
c) loud
d) tiny
e) vast
f) slow
g)fast

Answer: A & B.

Parallel universes are

Parallel universes are

a) an observation
b) a law
c) a hypothesis
d) a theory

Answer: C

The CMB and the Big Bang theory are related because

The CMB and the Big Bang theory are related because

a) the CMB is an observation that led to the development of the theory
b) Big Bang theory predicted the existence of the CMB
c) the Big Bang is a hypothesis that eventually became known as the CMB
d) the CMB is a fact, the Big Bang is a theory that is untested as a hypothesis.

Answer: B

The best evidence for dark matter in the Milky Way comes from the observation that the rotation curve

The best evidence for dark matter in the Milky Way comes from the observation that the rotation curve

a) is quite flat at a great distance from the center
b) rises swiftly in the interior
c) falls off and then rises again
d) has a peak at about 2,000 light-years away from the center

Answer: A

Astronomers observe two galaxies, A and B. Galaxy A has a recession velocity of 2,500 km/s, while Galaxy B has a recession velocity of 5,000 km/s. This means that

Astronomers observe two galaxies, A and B. Galaxy A has a recession velocity of 2,500 km/s, while Galaxy B has a recession velocity of 5,000 km/s. This means that

a) galaxy A is four times as far away as galaxy G
b) galaxy A is twice as far away as galaxy B
c) galaxy B is twice as far away as galaxy A
d) galaxy B is four times as far away as galaxy A.

Answer: C

Astronomers know active galactic nuclei are relatively small because

Astronomers know active galactic nuclei are relatively small because

a) variations in brightness occur quickly
b) variations in brightness occur slowly
c) variations in brightness are small
d) they have been directly imaged

Answer: A

No matter where you travel in space, you would observe very similar distributions of galaxies. This is an example of

No matter where you travel in space, you would observe very similar distributions of galaxies. This is an example of

a) isotropy
b) homogeneity
hydrostatic equilibrium
d) energy balance

Answer: B

The flat rotation curves of spiral galaxies imply that the distribution of mass resembles

The flat rotation curves of spiral galaxies imply that the distribution of mass resembles

a) the solar system; most mass is concentrated in the center
b) a wheel; the density remains the same as the radius increases
c) the light distribution of the galaxy; a large concentration occurs in the middle, but significant mass exists quite far out.
d) an invisible sphere much larger than the visible galaxy

Answer: D

An object that passes near a black hole

An object that passes near a black hole

a) always falls in because of gravity
b) is sucked in because of vacuum pressure
c) is pushed in by photon pressure
d) is deflected by the curvature of spacetime

e) sometimes falls in, sometimes deflected, it depends on how close it approaches

Answer: E

Ivana is standing in a small, windowless room. The force on her feet suddenly ceases. Which of the following conclusions can she draw

Ivana is standing in a small, windowless room. The force on her feet suddenly ceases. Which of the following conclusions can she draw

a) she is in an elevator, which is now accelerating downward
b) she is now ins pace, freely falling around Earth
c) the rocket she was in stopped accelerating upward
d) any of the above can be true

Answer: D

When photodisintegration starts in a star, a process begins that always results in a

When photodisintegration starts in a star, a process begins that always results in a

a) supernova
b) black hole
c) neutron star
d) pulsar

Answer: A

A pulsar changes in brightness because its size pulsates.

A pulsar changes in brightness because its size pulsates.

Answer: True

If you could draw a very large circle in space near a black hole, its circumference would be:

If you could draw a very large circle in space near a black hole, its circumference would be:

a) 2r
b) greater than 2r
c) less than 2r
d) can't be determined unless you know the size of the black hole

Answer: C

Imagine two spaceships travel toward each other. One spaceship travels to the right at the speed of 0.9c and the other travels to the left at 0.9c. The pilot of the spaceship travelling right shoots a yellow laser at the spaceship traveling left. The pilot of the spaceship traveling left observes:

Imagine two spaceships travel toward each other. One spaceship travels to the right at the speed of 0.9c and the other travels to the left at 0.9c. The pilot of the spaceship travelling right shoots a yellow laser at the spaceship traveling left. The pilot of the spaceship traveling left observes:

a) blue light traveling at c
b) blue light traveling at 1.9c
c) yellow light traveling at c
d) yellow light traveling at 1.9c

Answer: A

Pulsations in a Cepheid variable star are controlled by

Pulsations in a Cepheid variable star are controlled by 

a) the spin
b) the magnetic field
c) the ionization state of helium
d) the gravitational field

Answer: C

T/F A supernova can be as bright as its entire host galaxy

T/F A supernova can be as bright as its entire host galaxy

Answer: True

A low-mass star might become a supernova if and only if

A low-mass star might become a supernova if and only if

a) it is in a closer binary system
b) it is really cool
c) it is really dense
d) it has a lot of heavy elements in it

Answer: A

Suppose an atom has energy levels at 1, 3, 4, and 4.3. Which of the following is not a possible energy for an emitted photon?

Suppose an atom has energy levels at 1, 3, 4, and 4.3. Which of the following is not a possible energy for an emitted photon?

a) 2
b) 1
c) 1.3
d) 2.3

Answer: D

Most stars are

Most stars are

a) cool and low-luminosity
b) hot and low-luminosity
c) cool and high-luminosity
d) hot and high-luminosity

Answer: A

Two stars have equal luminosities, but star A has a much larger radius than star B. What can you say about these two stars?

Two stars have equal luminosities, but star A has a much larger radius than star B. What can you say about these two stars?

a) Star A is hotter than star B
b) Star A is cooler than star B
c)Star A is farther away than star B
d) Star A is brighter in our sky than star B

Answer: B

The solar neutrino problem pointed to a fundamental gap in our knowledge of

The solar neutrino problem pointed to a fundamental gap in our knowledge of 

a) nuclear fusion
b) neutrinos
c) hydrostatic equilibrium
d magnetic fields

Answer: B

In the proton-proton chain, four hydrogen nuclei are converted to a helium nucleus. This does not happen spontaneously on Earth because the process requires

In the proton-proton chain, four hydrogen nuclei are converted to a helium nucleus. This does not happen spontaneously on Earth because the process requires

a) vast amounts of hydrogen
b) very high temperatures and pressures
c) hydrostatic equilibrium
d) strong magnetic fields

Answer: B

T/F Sun spots can be comparable in size to the Earth.

T/F Sun spots can be comparable in size to the Earth.

Answer: True

T/F Neutrinos make it out of the Sun faster than photons.

T/F Neutrinos make it out of the Sun faster than photons.

Answer: True

T/F An atom can emit or absorb a photon of any wavelength.

T/F An atom can emit or absorb a photon of any wavelength.

Answer: False

T/F The brightness of a star in the sky tells you its luminosity.

T/F The brightness of a star in the sky tells you its luminosity.

Answer: False

T/F Red Stars have cooler surfaces than blue stars.

T/F Red Stars have cooler surfaces than blue stars.

Answer: True

If the wavelength of a beam of light were halved, how would that affect the frequency?

If the wavelength of a beam of light were halved, how would that affect the frequency?

a) the frequency would be four times larger
b) the frequency would be two times larger
c) the frequency would not change
d) the frequency would be two times smaller
e) the frequency would be for times smaller

Answer: B

The amplitude of light is:

The amplitude of light is:

a) its color
b) the frequency
c) the speed
d) the intensity

Answer: D

Lights act like (choose all that apply):

Lights act like (choose all that apply):

a) a wave, always
b) a particle, always
c) both a wave and particle
d) neither a wave nor a particle

Answer: C

Gamma ray telescopes are placed in space because:

Gamma ray telescopes are placed in space because:

a) gamma rays are too fast to be seen by stationary telescopes
b)gamma rays do not like the atmosphere
c) the atmosphere produces an abundance of gamma rays, so it overwhelms the signal from space
d) gamma rays are too dangerous to detect earth

Answer: B

Astronomers put telescopes in space be cause:

Astronomers put telescopes in space be cause:

a) they can
b) avoid atmospheric effects
c) to get closer to the stars
d) improve quantum efficiency

Answer: B

Light in the lowest energy end of the electromagnetic spectrum is in the _____ region.

Light in the lowest energy end of the electromagnetic spectrum is in the _____ region.

a)visible
b)gamma ray
c) ultraviolet
d)radio

Answer: D

A CCD camera is a better astronomical detector than the human eye because (choose all that apply):

A CCD camera is a better astronomical detector than the human eye because (choose all that apply):

a) It's awesome
b) chromatic aberration is minimized
c) they are not as heavy
d)their quantum efficiency is higher
e)the integration time can be longer
f)they can observe and capture photons beyond the visible

Answer: D, E & F.