Astronomy Chapter 7
What observational evidence supports the idea that Mercury once shrank by some 20 kilometers in radius?
the presence of many long, tall cliffs
The two most important processes in heating the interiors of the terrestrial worlds are __________.
(1) heat deposited by the process of formation; (2) heat released by radioactive decay
In general, which of the following are affected by a magnetic field?
charged particles or magnetized materials (such as iron)
The processes responsible for virtually all surface geology are _________.
impact cratering, volcanisms, tectonics, and erosion
The oxygen in Earth's atmosphere was released by
life
Based on all we know about the terrestrial worlds, what single factor appears to play the most important role in a terrestrial planet's geological destiny?
its size
Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a
hot spot
Earth has been gradually warming over the past few decades. Based on a great deal of evidence, scientists believe that this warming is caused by _____.
human activities that are increasing the concentration of greenhouse gases in Earth's atmosphere
Scientists can estimate the age of a planetary surface by counting __________
impact craters
Which heat source continues to contribute to Earth's internal heat?
radioactive decay
The extremely deep ocean Marianas Trench is a result of
subduction
Which of the following does NOT provide evidence that Mars once had abundant liquid water on its surface?
the presence of canali, discovered in the late 1800s by Giovanni Schiaparelli and mapped by Percival Lowell
How many of the five terrestrial worlds are considered "geologically dead"?
two
Which of the following is a strong greenhouse gas?
water vapor
What do we conclude if a planet has few impact craters of any size?
Other geological processes have wiped out craters.
What is the importance of the carbon dioxide (CO2) cycle?
It regulates the carbon dioxide concentration of our atmosphere, keeping temperatures moderate.
Which describes our understanding of flowing water on Mars?
It was important once, but no longer.
Seismic studies on Earth reveal a "lost continent" that held great human cities just a few thousand years ago but is now buried beneath the Atlantic seafloor.
This is not plausible. Plates move only a few centimeters per year, so a continent could not be subducted in a few thousand years. Neither could erosional processes bury a continent on the time scale of human civilization.
Which terrestrial world has the most atmospheric gas?
Venus
Australia is composed of relatively old and thick
continental crust
The earthquakes that occur in Southern California generally occur above a
fault
The slowly increasing distance between South America and Africa is due to
seafloor spreading
Layered ____ exposed by erosion can be seen when looking at the Grand Canyon in the United States.
sedimentary rock
Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?
size
_____ found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.
Seafloor crust
Which of the following is the most basic definition of a greenhouse gas?
a gas that absorbs infrared light
Suppose we use a baseball to represent Earth. On this scale, the other terrestrial worlds (Mercury, Venus, the Moon, and Mars) would range in size approximately from that of _________.
a golf ball to a baseball
What do we mean by a runaway greenhouse effect?
a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere
In general, what kind of terrestrial planet would you expect to have the thickest lithosphere?
a small planet
Suppose we represent Earth with a basketball. On this scale, most of the air in Earth's atmosphere would fit in a layer that is _________.
about the thickness of a sheet of paper
Where is the most CO2 that has outgassed from Earth's volcanoes?
locked up in rocks