Astronomy Chapter 9 Homework

25 July 2022
4.7 (114 reviews)
61 test answers

Unlock all answers in this set

Unlock answers (57)
question
Rank the five terrestrial worlds in order of size from smallest to largest.
answer
Moon, Mercury, Mars, Venus, Earth
question
What is differentiation in planetary geology?
answer
The process by which gravity separates materials according to density
question
When we say that a liquid has a high viscosity, we mean that it
answer
flows slowly like honey.
question
The lithosphere of a planet is the layer that consists of
answer
the rigid rocky material of the crust and uppermost portion of the mantle.
question
The core, mantle, and crust of a planet are defined by differences in their
answer
composition.
question
The terrestrial planet cores contain mostly metal because
answer
metals sank to the center during a time when the interiors were molten throughout.
question
Which of the following best describes convection?
answer
It is the process in which warm material expands and rises while cool material contracts and falls.
question
Which internal energy source produces heat by converting gravitational potential energy into thermal energy?
answer
both A and B
question
The main process by which heat flows upward through the lithosphere is
answer
conduction.
question
Which of the terrestrial worlds has the strongest magnetic field?
answer
Earth
question
Which of the following most likely explains why Venus does not have a strong magnetic field?
answer
Its rotation is too slow.
question
Which of the following has virtually no effect on the structure of a planet?
answer
its magnetic field
question
T/F: The strength of a rock depends on its composition, its temperature, and the surrounding pressure.
answer
True
question
T/F: Very high pressures, like those found deep within planetary interiors, can compress rocks so much that they stay solid even when temperatures are high enough to melt them under ordinary conditions.
answer
True
question
T/F: Earth is the only planet in the solar system known to have plate tectonics.
answer
True
question
What is the longest-lasting internal heat source responsible for geological activity?
answer
radioactive decay
question
Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?
answer
Size
question
Which two properties are most important in determining the surface temperature of a planet?
answer
distance from the Sun and atmosphere
question
About how large (on average) is an impact crater compared to the size of the impactor?
answer
10 times larger
question
When we see a region of a planet that is not as heavily cratered as other regions, we conclude that
answer
the surface in the region is younger than the surface in more heavily cratered regions.
question
Shallow-sloped shield volcanoes are made from lava that
answer
has a medium viscosity.
question
Which of the following describes erosion?
answer
the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather
question
What is basalt?
answer
a type of rock that makes relatively low-viscosity lava
question
How did the lunar maria form?
answer
Large impacts fractured the Moon's lithosphere, allowing lava to fill the impact basins.
question
Why does the Moon have a layer of powdery "soil" on its surface?
answer
It's the result of gradual erosion by micrometeorites striking the Moon.
question
Why do we think Mercury has so many tremendous cliffs?
answer
They were probably formed by tectonic stresses when the entire planet shrank as its core cooled.
question
Valles Marineris is a
answer
large canyon on Mars.
question
The polar caps on Mars are composed of
answer
mostly solid carbon dioxide and some water ice.
question
Choose the correct explanation of whether the discovery should be considered reasonable or surprising.
answer
This would be exciting, but not surprising. Heat from Martian volcanoes may well be enough to melt water under the Mars' surface.
question
How have we been able to construct detailed maps of surface features on Venus?
answer
by using radar from spacecraft that were sent to orbit Venus
question
Spacecraft have landed on all the terrestrial worlds except
answer
Spacecraft have landed on all of the terrestrial worlds.
question
Why are there fewer large craters on the seafloor than on the continents?
answer
The seafloor crust is younger than the continental crust.
question
Why is continental crust lower in density than seafloor crust?
answer
Continental crust is made from remelted seafloor crust and therefore only the lower-density material rises to form it.
question
How fast do plates move on Earth?
answer
a few centimeters per year
question
Deep trenches in the ocean mark places where
answer
one plate slides under another, returning older crust to the mantle.
question
T/F: In the inner solar system, the largest surface features are found on the largest planets.
answer
False
question
Choose the correct description of the conveyor-like action of plate tectonics on Earth.
answer
Earth's lithosphere is broken up into plates that float on the underlying mantle. The tops of the mantle's convection cells drag the bottoms of the plates, making them move. This movement causes spreading in some places and subduction in others.
question
What do we conclude if a planet has few impact craters of any size?
answer
Other geological processes have wiped out craters.
question
How many of the five terrestrial worlds have surfaces being constantly reshaped by plate tectonics?
answer
One
question
The cores of the terrestrial worlds are made mostly of metal because ______.
answer
metals sunk to the centers a long time ago when the interiors were molten throughout
question
Which of the following is not generally true of all the terrestrial world lithospheres?
answer
The lithosphere is broken into a set of large plates that float on the softer rock below.
question
Which internal heat source still generates heat within the terrestrial worlds today?
answer
Heat from radioactive decay.
question
The reason that small planets tend to lose interior heat faster than larger planets is essentially the same as the reason that ________.
answer
a large baked potato takes longer to cool than a small baked potato
question
Suppose we had a device that allowed us to see Earth's interior. If we looked at a typical region of the mantle, what would we see happening?
answer
On human time scales, the mantle looks like solid rock, so not much would be seen.
question
Recent evidence suggests that Mars once had a global magnetic field. Assuming this is true, which of the following could explain why Mars today lacks a global magnetic field like that of Earth?
answer
Mars's interior has cooled so much that its molten core layer no longer undergoes convection.
question
Which of the following most likely explains why Venus does not have a global magnetic field like Earth?
answer
Its rotation is too slow.
question
You discover an impact crater that is 10 kilometers across. Which of the following can you conclude?
answer
It was created by the impact of an object about 1 kilometer across.
question
Most of the Moon's surface is densely covered with craters, but we find relatively few craters within the lunar maria. What can we conclude?
answer
The maria formed after the heavy bombardment ended.
question
Which of the following is the underlying reason why Venus has so little wind erosion?
answer
its slow rotation
question
Which of the following best describes the geological histories of the Moon and Mercury?
answer
Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all.
question
Many scientists suspect that Venus has a stronger and thicker lithosphere than Earth. If this is true, which of the following could explain it?
answer
The high surface temperature that has "baked out" all the liquid water from Venus's crust and mantle.
question
All the following statements about Venus are true. Which one offers evidence of a global repaving about a billion years ago?
answer
Venus has relatively few impact craters and these craters are distributed fairly evenly over the entire planet.
question
What are the two geological features that appear to set Earth apart from all the other terrestrial worlds?
answer
plate tectonics and widespread erosion
question
Why are there fewer large impact craters on the Earth's seafloor than on the continents?
answer
Seafloor crust is younger than continental crust, so it has had less time in which to suffer impacts.
question
Why is Earth's continental crust lower in density than seafloor crust?
answer
Continental crust is made as the lowest-density seafloor crust melts and erupts to the surface near subduction zones.
question
Which two factors are most important to the existence of plate tectonics on Earth?
answer
mantle convection and a thin lithosphere
question
What's the fundamental reason that Mars has so little geological activity compared to Earth?
answer
its small size compared to Earth
question
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?
answer
its size
question
The choices describe four hypothetical planets. Which one would you expect to have the hottest interior? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.)
answer
Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months.
question
The choices describe four hypothetical planets. Which one's surface would you expect to be most crowded with impact craters? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.)
answer
Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days.
question
The choices describe four hypothetical planets. Which one would you expect to have the most features of erosion? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.)
answer
Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours.