If we say that a galaxy has a lookback time of 1 billion years, we mean that
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Its light traveled through space for 1 billion years to reach us
What is the approximate temperature of the universe today?
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3K
Suppose that inflation did not occur. In that case, the fact that the cosmic microwave
background has the same temperature in opposite directions of the sky would
,considered:
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surprising because those locations would never have been close enough
to have any light or matter exchanged between them
Red and orange stars are found evenly spread throughout the galactic disk, but blue
stars are typically found:
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only in or near star forming clouds. Blue stars are how, massive, and short-
lived.
Why do we use Hubble's law to estimate the distances of most distant galaxies, rather
than using white dwarf supernovae in all cases?
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We have not observed white dwarf supernovae in most gaalxies
What are the steps that describe how we use Cepheids as a tool to make cosmic
distance measurements?
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Step 1: Measure the period of the Cepheid's brightness variations
Step 2: Use the period-luminosity relation to determine the Cepheid's
luminosity
, Step 3: Calculate the Cepheid's distance from its luminosity and apparent
brightness
We can study how galaxies evolve because
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the farther away we look, the further back in time we see
Which of the following is an important starting assumption in models of galaxy
formation?
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some of the regions in the universe start out denser than others
Which evidence contradicts that the universe is expanding?
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1. Spiral galaxies move away from us 10% faster than elliptical galaxies at the
same distances
2. Irregular galaxies outside the Local Group are moving toward us
Which of the following are the three major categories of galaxies?
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elliptical galaxies, irregular galaxies, and spiral galaxies
If WIMPs really exist and make up most of the dark matter in galaxies, which of the
following is one of their characteristics?
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- they tend to orbit at large distances from the galactic center
- they are subatomic particles
- they can neither emit nor absorb light
Assume the Hubble's constant is 22 kilometers per second per million light-years.
How fast would we expect a galaxy 100 million light-years away to be moving?
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away from us at 22, 000 km/s
Which of the following best sums up current scientific thinking about the nature of
dark energy?
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Dark energy probably exists, but we have little (if any) idea what it is
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Its light traveled through space for 1 billion years to reach us
What is the approximate temperature of the universe today?
Give this one a try later!
3K
Suppose that inflation did not occur. In that case, the fact that the cosmic microwave
background has the same temperature in opposite directions of the sky would
,considered:
Give this one a try later!
surprising because those locations would never have been close enough
to have any light or matter exchanged between them
Red and orange stars are found evenly spread throughout the galactic disk, but blue
stars are typically found:
Give this one a try later!
only in or near star forming clouds. Blue stars are how, massive, and short-
lived.
Why do we use Hubble's law to estimate the distances of most distant galaxies, rather
than using white dwarf supernovae in all cases?
Give this one a try later!
We have not observed white dwarf supernovae in most gaalxies
What are the steps that describe how we use Cepheids as a tool to make cosmic
distance measurements?
Give this one a try later!
Step 1: Measure the period of the Cepheid's brightness variations
Step 2: Use the period-luminosity relation to determine the Cepheid's
luminosity
, Step 3: Calculate the Cepheid's distance from its luminosity and apparent
brightness
We can study how galaxies evolve because
Give this one a try later!
the farther away we look, the further back in time we see
Which of the following is an important starting assumption in models of galaxy
formation?
Give this one a try later!
some of the regions in the universe start out denser than others
Which evidence contradicts that the universe is expanding?
Give this one a try later!
1. Spiral galaxies move away from us 10% faster than elliptical galaxies at the
same distances
2. Irregular galaxies outside the Local Group are moving toward us
Which of the following are the three major categories of galaxies?
, Give this one a try later!
elliptical galaxies, irregular galaxies, and spiral galaxies
If WIMPs really exist and make up most of the dark matter in galaxies, which of the
following is one of their characteristics?
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- they tend to orbit at large distances from the galactic center
- they are subatomic particles
- they can neither emit nor absorb light
Assume the Hubble's constant is 22 kilometers per second per million light-years.
How fast would we expect a galaxy 100 million light-years away to be moving?
Give this one a try later!
away from us at 22, 000 km/s
Which of the following best sums up current scientific thinking about the nature of
dark energy?
Give this one a try later!
Dark energy probably exists, but we have little (if any) idea what it is
