Chapter 7 The moon

The lunar regolith, shown here imprinted with an Apollo astronaut's bootprint, ____.

covers the surface of the Moon is composed of rock pulverized by impacts is tens of meters deep

Right now, as a result of tidal braking, ____. (Select all that apply.)

days on Earth are slowly getting longer the distance to the Moon is increasing Earth only sees one side of the Moon

Apollo mission results show that Moon and Earth rocks have differences; for example, a lack of low-melting-point metals in Moon rocks. The density and structure suggest the Moon has less iron than Earth. What do these suggest is a likely model of the Moon's formation?

A Mars-sized object hit Earth after Earth differentiated, splattering low-density mantle and crust material into orbit to form the Moon.

Use the image to match the expressions and descriptions.

C The average force of the Moon on Earth B - C The strength of the tidal force in the near bulge A The strength of the Moon's gravity at a point on Earth B The strength of the Moon's gravity in the near bulge

Select all that are reasons there is ice on the Moon.

Deep crater bottoms are shielded from sunlight, so it never gets hot enough to melt ice there. Comets have struck the Moon, vaporizing and depositing water.

How many high and low tides are there per day?

There are two high tides and two low tides per day.

The best explanation for why Earth has a tidal bulge opposite the Moon is that ____.

the Moon pulls the center and near side of Earth more strongly than the far side

A peculiarity of the Moon's structure is that ____.

the crust is more than twice as thick on the far side than the near side

The force of gravity between the Sun and Earth is stronger than the force of gravity between the Moon and the Sun. However, the Sun's tidal force on Earth is smaller than the Moon's. This is because ____. (Choose the best answer.)

the diameter of Earth is a smaller fraction of the distance to the Sun than it is of the distance to the Moon

The tides are strongest on the parts of Earth nearest to (D) and farthest from (B) the Moon. The reason that there are not strong tidal bulges at points A and C is because ____.

the gravitational force of the Moon at the surface at A and C is about the same as the average force of the Moon on Earth

Select all that are necessary for tidal braking to occur.

A differential gravitational force exerted on a quickly spinning object Friction between tidal bulges and a spinning object

There are roughly___hours between high tide and low tide

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Tidal interactions occur throughout the universe, between planets and moons, black holes and stars, and even between different galaxies. Tidal forces happen because the strength of ____changes with_____

Blank 1: gravity Blank 2: distance, d, or distance squared

Sometimes the Sun's tidal effect on Earth adds to the Moon's, producing a______ tide.When the Sun's tides occur six hours offset from the Moon's, the resulting weaker tide is called a ______tide.

Blank 1: spring Blank 2: neap

During what phases could a spring tide occur?

New moon Full moon

The streak-like features indicated by the arrows labeled "A" are ____.

Rays

Match the geometry and conditions to the tides.

Spring tide- Tides are higher than average, Sune-Earth-Moon forms a liine Neap tide-Sun-Ear-Moon forms a right angle, tides arn lower than average.

Why are there more maria on the Moon's near side than on its far side?

The asymmetry in the Moon's interior made the far side crust cool sooner and become thicker.

Select consequences of the Moon's lack of atmosphere.

The sky is black during the day. There are large swings in surface temperature.

How long is a day on the Moon?

1 lunar month (the time from full moon to full moon)

Arrange the following sentences to describe how impact features are formed on the Moon, from the first step at the top to the last at the bottom.

1. The impactor hits the Moon's surface at high speed. 2. The impactor disintegrates into a cloud of vaporized rock and fragments 3. A hole forms, with a size depending on the mass and velocity of the impactor. 4. Vaporized rock forces the surrounding surface rock out into a circular, raised rim. 5. Sometimes the compressed rock beneath the crater rebounds and creates a central peak in the crater.

Select all the choices that are true of the interiors of the Moon and Earth:

A crust/mantle/core structure Crusts composed of silicate rocks

Match the descriptions with the correct layers of the Moon's internal structure.

Core- partialy molten iron, slightly off center Mantle- widest internal region, contains lots of olvine Crust- where regolith is found, rich in aluminum

Match each prediction to the appropriate hypothesis of the Moon's formation.

Earth captured a fully formed Moon.- Earth and the Moon have very different chemical compositions. Earth and Moon formed at the same time.- Earth and the Moon have very similar chemical compositions. The Moon formed from material spun off Earth due to Earth's rapid rotation.- The Moon has a chemical composition identical to Earth's crust. The Moon formed as a result of a collision between Earth and a large object.- Earth and the Moon share many compositional similarities.

Earth and the Moon are next to each other in space, so why does the Moon have so many more impact craters than Earth?

Earth's craters have been removed by erosion and plate tectonics

The Moon exerts a tidal braking force on Earth because ____.

Earth's rotation carries the tidal bulge ahead of the Moon

True or false: On Earth, tides caused by the Sun are less noticeable than lunar tides because Earth takes a year to orbit the Sun while the Moon only takes a month to orbit Earth.

False Reason: We experience two solar tides (and two lunar tides) each day because Earth rotates. The Sun is much farther away, so the change in its gravitational force from one side of Earth to the other is small.

What is the best account of the Moon's lack of atmosphere?

Gas present immediately after formation escaped molecule by molecule, because of the Moon's weak gravity and its proximity to the Sun.

Match the elements with regions on the Moon where they are likely to be concentrated.

Iron, titanium, magnesium Lunar mare regions Calcium, aluminum silicates Lunar highlands Hydrogen, helium Not prevalent on the Moon

In what ways is the Moon different from the other large satellites in the Solar System?

It is large relative to its planet. It does not orbit directly above the equator of its planet.

Select all the processes important for forming lunar maria.

Lava from the mantle flooding craters on the early Moon Large objects hitting the Moon

Select all the statements that correctly describe the rays seen on the Moon's surface.

Long, light streaks of pulverized rock Radiate out from craters

Select all the lunar features thought to form as a direct or indirect result of impacts.

Lunar rays Maria Craters

Select the properties listed that would be true of region B. The other properties are true of region A.

Made of basalt Younger; 3 billion years old

Match the alignments of Sun, Earth, and Moon tot he type of tides they produce and a time that tide would be maximum.

Spring tide- full moon, new moon, about midnight Neap tide- first-quarter moon, third quarter moon, about 6 am

Which of the following is evidence against the hypothesis that Earth and the Moon formed together side-by-side from a common cloud of gas and dust?

The Moon has a lower fraction of iron than Earth does.

Select all of the reasons the Moon has a heavily cratered surface but Earth does not.

The Moon has no atmosphere. The Moon has little geological activity.

Earth has an atmosphere, but the Moon doesn't. Select all the reasons why.

The Moon has too little mass so it lacks enough gravity to hold onto an atmosphere. The Moon has no volcanic activity producing gases. The Moon is so cold that any gas is frozen onto the surface.

Earth's ocean plates are rich in basalt and sink down into the mantle at continental edges (subduction zones). However, there are not subduction zones on the Moon at the edge of the maria and the highlands. Select all the reasons why.

The Moon's crust is a solid layer. The Moon's interior is cold enough that there are no convection currents.

Which details about the Moon are explained by the violent-birth hypothesis?

The Moon's iron core is very small for its size. The Moon has little water. The Moon's chemical composition is similar to Earth's but not identical.

Match the descriptions of their interiors with the Moon, Earth, or both.

The moon- Solid mantle thinner crust on one side Earth- completely molten layer in core, strong magnetic field both- silicate-rich crust, olivine rich mantle

Which is the cause of the Moon's synchronous rotation?

Tidal force from Earth slowed the Moon's rotation.

Match the terms related to tides to their meanings.

Tide- The regular change in the height of the oceans- Tidal bulge- A bulge in ocean waters caused by the differential gravitational force of the Moon Solar tides- Tides caused by the Sun; smaller than the Moon's tides Tidal braking- A slowing of Earth's rotation due to drag on the tidal bulges

The hypotheses for the formation of the Moon make different predictions about the Moon's chemical composition. Select all that are disproved by the fact that the Moon has a composition similar, but not identical, to Earth's.

capture hypothesis fission hypothesis twin formation hypothesis

The difference between the strong gravitational attraction by the Moon on Earth's near side and the weak attraction on its far side is called a _______gravitational force.

differential

Tidal bulges result ____. (Select all that apply.)

from a "differential" gravitational force from the difference between the force of gravity (from another object) on one side of an object and the force of gravity on the middle

The Moon lacks the convection currents needed to power plate tectonics because ____.

it cooled off faster than Earth

The Moon appears different in the left and right sides of the image because ____.

it has an elliptical orbit angular size depends on distance

The Moon appears larger and smaller at different times because ____ and so its ____ changes.

its orbit is an ellipse; distance from us

The Moon's lack of atmosphere results in a ____ swing of day-night temperature than we have on Earth.

much larger

The blanket of chunks of rock and fine rock powder that covers the Moon is called _____

regolith

The long, straight canyon shown is an example of a lunar ____ that may have been formed by crustal shifting.

rille

For which of the following properties does the Moon have the largest value compared to the other planetary satellites (not moons of dwarf planets) in the Solar System?

the ratio of satellite mass to planet mass

The differential gravitational force of the Moon acting on Earth causes Earth to slow down, a phenomenon known as ____.

tidal braking