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ASTR 107 Exam 3 Study Guide

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Ch 19-24
Roman Jordan
Quiz by Roman Jordan, updated 7 months ago
Roman Jordan
Created by Roman Jordan 8 months ago
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Question 1

Question
What does it mean that the universe is homogenous?
Answer
  • 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

Question 2

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

Question 3

Question
Cosmological redshifts are calculated from observations of spectral lines from
Answer
  • individual stars in different galaxies
  • clouds of dust and gas in different galaxies
  • spectra of entire galaxies
  • rotations of the disks of distant galaxies

Question 4

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

Question 5

Question
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
Answer
  • 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

Question 6

Question
The Big Bang theory predicted
Answer
  • the Hubble law
  • the cosmic microwave background radiation
  • the cosmological principle
  • the abundance of helium
  • the period-luminosity relationship of Cepheid variables

Question 7

Question
The simplest way to estimate the age of the universe is from
Answer
  • using the slope of Hubble's Law
  • the age of Moon rocks
  • models of stellar evolution
  • measurements of the abundances of elements

Question 8

Question
The CMB includes information about
Answer
  • 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

Question 9

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

Question 10

Question
If the density of the universe is higher than the critical density, the universe will
Answer
  • expand forever
  • expand, but gradually slow down
  • eventually collapse
  • neither expand nor contract

Question 11

Question
Dark energy has been hypothesized to solve which problem?
Answer
  • 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

Question 12

Question
What problems of cosmology does inflation solve?
Answer
  • flatness
  • horizon
  • fluctuation
  • sphere

Question 13

Question
The first stars formed in the universe had [blank_start]fewer[blank_end] heavy elements and [blank_start]higher[blank_end] mass than the stars formed today.
Answer
  • fewer
  • more
  • higher
  • lower

Question 14

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

Question 15

Question
Place the following in order of size, from smallest to largest. [blank_start]a star[blank_end] [blank_start]star clusters[blank_end] [blank_start]a galaxy[blank_end][blank_start]the Local Group[blank_end] [blank_start]Virgo Cluster[blank_end][blank_start]Laniakea[blank_end] [blank_start]a wall[blank_end]
Answer
  • a star
  • star clusters
  • a galaxy
  • the Local Group
  • Virgo Cluster
  • Laniakea
  • a wall

Question 16

Question
The dominant force in the formation of galaxies is
Answer
  • gravity
  • angular momentum
  • the electromagnetic force
  • the strong nuclear force

Question 17

Question
Larger galaxies form from the merging of small protogalaxies. That process is similar to the formation of:
Answer
  • stars
  • planets
  • molecular clouds
  • asteroids

Question 18

Question
Which of the following is a characteristic difference between cold and hot dark matter?
Answer
  • temperature
  • ability to emit radiation
  • the way they clump under the influence of gravity
  • mass density

Question 19

Question
The dominant factor in the formation of galaxies is the distribution of [blank_start]dark matter[blank_end] in the early universe.
Answer
  • dark matter
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