ASTRONOMY: Cratered Worlds: Moon

In the absence of any air, the lunar surface experiences much greater temperature extremes than the surface of Earth, even though Earth is virtually the same distance from the Sun. During the long lunar night (which, like the lunar day, lasts two Earth weeks), the temperature drops to about:

-280° F

Although the diameter of the Moon is 27% of the Earth, the Moon's mass is only ________ percent of the Earth.

1.2

The largest _______ on the Moon is near its South Pole and has a diameter of 55 miles.

Crater

The lunar ______ temperature gets up to 225° F.

Day

Impactors striking the moon are traveling at such high rates of speed that lunar craters are always:

Symmetrical and circular

Both the earth and moon formed 4.5 to 4.6 billion years ago. True or False?

True

Compared to the Earth, the moon is depleted in iron and other metals. True or False?

True

Due to its small size, the moon has no atmosphere. True or False?

True

The moon has ______ the gravity of the Earth.

1/6th

The size of the impact crater is ____ times the diameter of the impactor.

10 to 15

The maria are much less cratered than the highlands, and cover just ________ of the lunar surface, mostly on the side of the Moon that faces Earth.

17%

When an lunar impactor strikes the moon, it penetrates ____ times its own diameter before stopping.

2-3

The diameter of the Moon is approximately ___________ miles.

2200

In miles, what is the average distance from the Earth to the Moon?

238,000 miles

The major mare volcanism, which involved the release of lava from hundreds of kilometers below the surface, ended about ____ billion years ago.

3.3

Aristarchus of Samos calculated the distance from the Earth to the Moon as _________ Earth radiii.

60

Studies of the Moon's interior carried out with seismometers taken to the Moon as part of the Apollo program confirm the __________ of a large metal core.

Absence

The lunar highlands are made of relatively low-density rock called _______ that solidified on the cooling Moon like slag floating on the top of a smelter.

Anorthosite

Most of the crust of the Moon (83%) consists of silicate rocks called:

Anorthosites

Humans first walked on the Moon in July 20, 1969 during the __________ mission.

Apollo 11

Today, we know that the maria consist mostly of dark-colored _________ (volcanic lava) laid down in volcanic eruptions billions of years ago.

Basalt

The moon illusion is when the moon looks _______ on the horizon than when it is higher in the sky.

Bigger

The word regolith translates as:

Blanket + rock

The word crater comes from the Greek word for:

Bowl

An early model for the formation of the moon, called the _______ hypothesis, is that Moon formed elsewhere in the solar system and was captured by Earth.

Capture

Large craters on the moon will have ______. These are made by a splash effect caused by the kinetic energy of the impacting object being turned to heat and melting some lunar material.

Central peaks

Surrounding the rim is an ejecta blanket consisting of material thrown out by the explosion. This debris falls back to create a rough, hilly region, typically about as wide as the:

Crater diameter

Some of these streams of ejecta can extend for hundreds or even thousands of kilometers from the crater, creating the bright ________ that are prominent in lunar photos taken near full phase.

Crater rays

The lunar highlands formed early in lunar history (4.1 to 4.4 billion years ago) ago), the highlands are also extremely heavily _______, bearing the scars of all those billions of years of impacts by interplanetary debris

Cratered

Much of the moon is covered by circular holes. These are impact ________ which formed when an asteroid or comet collided with the Moon.

Craters

The giant impact model hypothesizes Theia striking the Earth with a glancing blow, vaporizing itself and throwing parts of the Earth's _________ into orbit around the Earth. This model explains the low density of the moon compared to the Earth.

Crust and mantle

The moon is composed of the same silicates found in the ______ of the Earth.

Crust and mantle

Aristarchus of Samos calculated both the size of the Moon and the ___________ circa 200 B.C.E.

Distance to the Moon

Surrounding the rim is an _______ consisting of material thrown out by the explosion. This debris falls back to create a rough, hilly region, typically about as wide as the crater diameter.

Ejecta blanket

During a full moon, the moon is larger in diameter on the horizon than at zenith. True or False?

False

What two phases are the best times to observe the moon with a telescope if you want to see detail of craters and hills?

First quarter and Last quarter

Which two phases of the moon are best for observing topographic detail (e.g. craters)?

First quarter and last quarter

An early model for the formation of the moon, called the _______ hypothesis, is that the Moon was once part of Earth, but somehow separated from it early in their history.

Fission

Which phase of the moon is best for observing the contrast in brightness between the maria and the lunar highlands?

Full moon

Currently, the most plausible explanation for the origin of the moon is the:

Giant impact hypothesis

One of the first geologists to propose that lunar craters were the result of impacts was ______, a scientist with the US Geological Survey in the 1890s.

Grove K. Gilbert

The maria were formed when lava flows partly filled the huge depressions called _______, which had been produced by collisions of large chunks of material with the Moon relatively early in its history.

Impact basins

The fission hypothesis for the origin of the moon has been falsified because modern calculations have shown that this sort of spontaneous fission or splitting is:

Impossible

The impactor hypothesized to have struck the earth to form the moon is named Theia because:

In mythology, Theia is the mother of the moon.

What typically happens to the impactor when it strikes the lunar surface?

It mostly vaporizes

The reason the moon temperature is so wide-ranging is because the moon:

Lacks an atmosphere

This __________, like so much else on the Moon, is the product of impacts. Each cratering event, large or small, breaks up the rock of the lunar surface and scatters the fragments. Ultimately, billions of years of impacts have reduced much of the surface layer to particles about the size of dust or sand.

Lunar dust

The light-colored areas on the Moon are known as the _______ and are 4.5 billion years old.

Lunar highlands

Which are older: lunar highlands or maria?

Lunar highlands

Giant impacts early in the Moon's history created huge impact basins which then filled with lava from the lunar interior forming:

Maria

The dark-colored areas on the Moon are 3.1-3.8 billion years old and are known as:

Maria

The giant impact hypothesis envisions Earth being struck obliquely by an object approximately one-tenth Earth's mass—a "bullet" about the size of _____. This is very nearly the largest impact Earth could experience without being shattered.

Mars

What planet looks very similar to the moon?

Mercury

All the Apollo mission landed on the ______ side of the Moon.

Near

What Apollo 11 astronaut said after stepping onto the moon said, "The surface is fine and powdery. I can pick it up loosely with my toe. But I can see the footprints of my boots and the treads in the fine sandy particles."?

Neil Armstrong

The lunar ______ temperature drops to -243°F

Night

When an impactor strikes the lunar surface, its energy of motion is transferred into a shock wave and into heat. The shock wave fractures the rock of the lunar surface, while the expanding silicate vapor generates an explosion similar to that of a ______ detonated at ground level.

Nuclear bomb

The diameter of the Moon is about _________ the diameter of the Earth.

One-quarter

The flat bottom and central peak of a lunar crater are created by the _______ that partially fills in the crater.

Rebound to the crust

The dust on the surface of the moon is known as:

Regolith

_______ on the moon is glassy dust from previous meteorites.

Regolith

The _____ of a lunar crater is turned up by the force of the explosion, so it rises above both the floor and the adjacent terrain.

Rim

Thousands of individual craters on the moon have been named, however, mostly for great _______ and philosophers

Scientists

The word mare translates as:

Sea

Apollo 11 landed in a mare called the:

Sea of Tranquility

Centuries ago, early lunar observers thought that the Moon had continents and oceans and that it was a possible abode of life. They called the dark areas ____(maria in Latin, or mare in the singular, pronounced "mah ray").

Seas

Observing a full moon with a telescope is difficult because without a filter it is often too bright and without _________, craters and hills are tough to see.

Shadows

Since the moon is significantly less dense than the Earth, the moon must be composed almost entirely of ______ rock.

Silicate

An early model for the formation of the moon, called the _______ hypothesis, is that the Moon formed together with (but independent of) Earth, as we believe many moons of the outer planets formed.

Sister

Around the rim of an impact crater, landslides create a series of:

Terraces

Which is more dense: the Earth or the moon?

The Earth

In the absence of any air, the lunar surface experiences much greater temperature extremes than the surface of Earth, even though Earth is virtually the same distance from the Sun. Near local noon, when the Sun is highest in the sky, the temperature of the dark lunar soil rises above ________.

The boiling point of water

Grove K. Gilbert pointed out that the bigger lunar craters are larger and have different shapes from known volcanic craters on Earth. True or False?

True

Rocks from the moon date from 3.3 to 4.4 billion years old. True or False?

True

Since the moon has little or no geologic activity, the surface rocks are substantially older than rocks on Earth. True or False?

True

The moon doesn't have the gravity to keep an atmosphere. True or False?

True

The moon has a density of 3.3 g/cm³: True or False?

True

The basalt on the Moon is very similar in composition to the crust ___________ of Earth or to the lavas erupted by many terrestrial volcanoes.

Under the oceans

Among the most prominent craters are those named for Plato, Copernicus, Tycho, and Kepler. Galileo only has a small crater, however, reflecting his low standing among the _____ who made some of the first lunar maps.

Vatican scientists

If the moon was captured by the Earth, the orbit of the moon would be:

Very eccentric

Since impact craters are rare on Earth, most astronomers and geologist in the 19th century thought lunar craters were:

Volcanic craters

Grove K. Gilbert's hypothesis that lunar craters are impact craters wasn't accepted by the scientific community until after ______ when they recognized the similarity between impact craters and explosion craters.

World War I