Roman Jordan
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Ch 19-24

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ASTR 107 Exam 3 Study Guide

Question 1 of 19

1

What does it mean that the universe is homogenous?

Select one of the following:

  • The universe looks the same from every perspective

  • Galaxies are generally distributed evenly throughout the universe

  • All stars in all galaxies have planetary systems just like ours

  • The universe has looked the same at all times in its history

Explanation

Question 2 of 19

1

What do astronomers mean when they say that the universe is isotropic?

Select one of the following:

  • More distant parts of the universe look just like nearby parts

  • Intergalactic gas has the same density everywhere in the universe

  • The laws of physics apply everywhere in the universe

  • The universe is the same in every direction

Explanation

Question 3 of 19

1

Cosmological redshifts are calculated from observations of spectral lines from

Select one of the following:

  • individual stars in different galaxies

  • clouds of dust and gas in different galaxies

  • spectra of entire galaxies

  • rotations of the disks of distant galaxies

Explanation

Question 4 of 19

1

Astronomers observe that all galaxies are moving away from the Milky Way. According to the cosmological principle, this observation suggests that

Select one of the following:

  • the Milky Way is at the center of the universe

  • the Milky Way must be at the center of the expansion

  • the Big Bang occurred at the current location of the Milky Way

  • an observer in a distant galaxy would make the same observation

Explanation

Question 5 of 19

1

Some galaxies have redshifts (z) that if equated to Vr/c correspond to velocities greater than the speed of light. Special relativity is not violated

Select one of the following:

  • because of relativistic beaming

  • because it's a trick of the measurement angle

  • because redshifts carry no information

  • because those velocities do not measure motion through space

Explanation

Question 6 of 19

1

The Big Bang theory predicted

Select one or more of the following:

  • the Hubble law

  • the cosmic microwave background radiation

  • the cosmological principle

  • the abundance of helium

  • the period-luminosity relationship of Cepheid variables

Explanation

Question 7 of 19

1

The simplest way to estimate the age of the universe is from

Select one of the following:

  • using the slope of Hubble's Law

  • the age of Moon rocks

  • models of stellar evolution

  • measurements of the abundances of elements

Explanation

Question 8 of 19

1

The CMB includes information about

Select one or more of the following:

  • the age of the universe

  • the temperature of the early universe

  • the density of the early universe

  • density fluctuations in the early universe

  • the motion of Earth around the center of the Milky Way

Explanation

Question 9 of 19

1

Repeated measurements showing that the current helium abundance is much less than the value predicted by the Big Bang would imply that

Select one of the following:

  • some part of the Big Bang theory is incorrect or incomplete

  • the current helium abundance is wrong

  • scientists don't know how to measure helium abundances

Explanation

Question 10 of 19

1

If the density of the universe is higher than the critical density, the universe will

Select one of the following:

  • expand forever

  • expand, but gradually slow down

  • eventually collapse

  • neither expand nor contract

Explanation

Question 11 of 19

1

Dark energy has been hypothesized to solve which problem?

Select one of the following:

  • the universe is expanding

  • the cosmic microwave background radiation is too smooth

  • the expansion of the universe is accelerating

  • stars orbit the centers of galaxies too fast

Explanation

Question 12 of 19

1

What problems of cosmology does inflation solve?

Select one or more of the following:

  • flatness

  • horizon

  • fluctuation

  • sphere

Explanation

Question 13 of 19

1

Select from the dropdown lists to complete the text.

The first stars formed in the universe had ( fewer, more ) heavy elements and ( higher, lower ) mass than the stars formed today.

Explanation

Question 14 of 19

1

We expect the kinds of galaxies that we see at a redshift of z = 4 to be:

Select one of the following:

  • much like we see today

  • smaller and much more irregular looking than today

  • far more numerous but with more spiral galaxies

  • larger versions of what we see today

Explanation

Question 15 of 19

1

Place the following in order of size, from smallest to largest.




Drag and drop to complete the text.

    a star
    star clusters
    a galaxy
    the Local Group
    Virgo Cluster
    Laniakea
    a wall

Explanation

Question 16 of 19

1

The dominant force in the formation of galaxies is

Select one of the following:

  • gravity

  • angular momentum

  • the electromagnetic force

  • the strong nuclear force

Explanation

Question 17 of 19

1

Larger galaxies form from the merging of small protogalaxies. That process is similar to the formation of:

Select one of the following:

  • stars

  • planets

  • molecular clouds

  • asteroids

Explanation

Question 18 of 19

1

Which of the following is a characteristic difference between cold and hot dark matter?

Select one or more of the following:

  • temperature

  • ability to emit radiation

  • the way they clump under the influence of gravity

  • mass density

Explanation

Question 19 of 19

1

Fill the blank space to complete the text.

The dominant factor in the formation of galaxies is the distribution of in the early universe.

Explanation

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