Astronomy 101 Chapters 7 and 8 – Flashcards
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Which of the following statements would be true if there were no greenhouse effect?
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There would be no life on Earth.
There would be no liquid water on Earth.
The temperature on Earth would be much colder.
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Why is the sky blue?
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The wavelength of blue light is roughly the same size as air molecules.
Scattering is most efficient for wavelengths that are the same size as the scatterers, so blue light is scattered much more than red light, which leads to a blue sky.
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Earth's average density is best described by which of the following statements?
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It is higher than the density of surface rocks.
Earth's interior therefore has a much higher density than the rock at the surface.
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What are the two main constituents of Earth's atmosphere?
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O2 and N2
Oxygen (~ 21%) and nitrogen (~ 78%) make up the bulk of Earth's atmosphere.
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What natural phenomenon on Earth provides information on the structure of Earth's core?
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Earthquakes
The seismic waves produced by earthquakes provide information about the structure of Earth's core.
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Which of the following is plate tectonics NOT responsible for?
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Erosion
Erosion is the wearing away of surface features, usually due to wind and water on Earth. It is not caused by plate tectonics.
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When two tectonic plates collide:
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they continue moving, producing a variety of large deformations.
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The region around Earth where the magnetic field traps charged particles is the:
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Van Allen Radiation Belts.
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At what phase would tidal variation be the least during the entire day?
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first quarter
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What is the primary cause of erosion on the Moon?
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Impact cratering
Meteoroid impacts have battered the surface of the Moon for billions of years and are the primary cause of erosion.
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The wide variation in the lunar surface temperature is due to its lack of _______.
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an atmosphere
An atmosphere acts as an insulating blanket, keeping temperature fluctuations from being too extreme.
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When did most of the cratering on the Moon occur?
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About 4 billion years ago
Most of the Moon's cratering occurred during an extended period of intense meteoritic bombardment early in its history, roughly 4 billion years ago.
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If you were standing on the far side of the Moon, which object would you never see?
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Earth
From the far side, you would never see Earth because the near side of the Moon always faces Earth.
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Why doesn't the far side of the Moon have any large maria?
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The lunar crust is thicker on the far side.
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What caused the large equatorial lunar bulge?
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Earth's past tidal force on the Moon when it was much closer
The large equatorial lunar bulge was frozen in place as the Moon solidified.
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What caused the scarps found on Mercury?
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Cooling of the planet and shrinking of the crust
Mercury's surface split as the crust shrank. One side of the split moved upward relative to the other side.
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What is the current leading theory for the Moon's formation?
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Impact of a large object with the early Earth, followed by coalescence and capture of the resulting fragments
Lunar formation is not completely understood, but this hybrid impact theory explains most of the observed facts.
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The Moon is locked in synchronous orbit with Earth. How many times does the Moon rotate every time it completes one revolution?
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One
Synchronous orbit means one rotation for each revolution.
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Mercury experiences extreme high and low temperatures between night and day because:
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it has no true atmosphere to moderate temperatures over the globe.
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Comparing the densities of the Moon and Mercury, we find:
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the Moon's is similar to Earth's crust, while Mercury's is similar to the entire Earth.
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The oldest known features of Mercury's surface formed:
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just under 4 billion years ago.
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What did radar astronomers find in the polar regions of Mercury?
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water ice that never melts in the deep craters
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Which type of feature is the best evidence of lunar volcanism?
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rilles associated with lava flows accompanying the mare formation
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Mercury's surface most resembles which of these?
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the lunar far side
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How does Mercury's magnetic field compare to our own?
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It is 1/100th as strong as ours, but does deflect the solar wind to some degree.
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Mercury's evolution was different from the Moon's because:
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dense Mercury had an iron core that shrank, creating the lobate scarps.
