Section 9.3
1. Dark regions on the moon are called maria
2. Cratered regions on the moon are called terrae
3. First robot lunar landers 1966 provided lots of information about lunar interior,
surface, and atmosphere
4. Craters are the dominant features of the lunar surface
5. The ranger series in 1964-65 used television cameras to show image of the moons
Surface
6. In 1966 the USSR and US began the space race and created a series of robot
landers
7. Craters were formed by meteriods falling toward the moon, and the impact created
the craters
8. The regolith is the layer of surface debris on the moon, it is 40m thick on the edge of
hadley lrille
9. Some lunar features are volcanic such as maria, they volcanic basalts
10. Mascons are intrusions of dense mantle material into the fractured crust beneath the
maria
11. Other volcanic features are rilles and sinuous rilles
Section 9.4
Chemical Composition
 Lunar rocks are similar to the Earths crust
 The elements aluminum, calcium, chromium, titanium, and uranium are more
abundant rocks on the moon.
 Easily vaporized elements such as sodium, chloride, zinc, and lead are low and
abundance compared with terrestrial rock.
Ages of Lunar Samples
Oldest rocks are 4.5 billion years old and solidified shortly after the formation of the moon.
Agees and Cratering
Crater density is the number of craters of different sizes on a given amount of lunar surface
area.
Crater density increases with age.
Crater Saturation is when new impacts obliterate as many craters as they produce.
History of the Lunar Surface
The age makes it possible to determine the rate at which craters were formed throughout
the moons history.
The terrae are only 15% older than maria.
Section 9.5
1. The moon's atmosphere consists primarily of helium, neon, argon, and hydrogen
2. If compressed to the density of water, the moon's atmosphere would only fill a cube
1 meter on each side
3. The thin atmosphere poorly insulates the surface
4. The temperature on the moon at high noon can reach 260 degrees fahrenheit
5. The temperature before dawn is only -280 degrees fahrenheit
6. Due to the dark sky planets and stars are even visible at high noon
7. About 50 grams of solar wind gases are captured by the moon from solar wind each
second
8. The lunar escape velocity is so low that lighter gases such as hydrogen and helium
escape into space within an hour
9. Heavier gases are swept away by solar wind or are absorbed by rocks on the lunar
surface
10. Most of the water molecules escape to space, but some migrate to the lunar poles,
they are in extremely cold floors of craters that have never seen sunlight
11. The water molecules can condense as ice crystals
12. Lunar prospector detected surface hydrogen atoms presumably in water molecules.
Section 9.6
1. The Moon’s mass has been accurately determined by measuring its orbital periods
and the distances of satellites orbiting the Moon.
2. The mass of the Moon was found to be 7.4 X 10 ^22 kg. Thus, the Moon is 1/81 the
mass of the Earth (meaning the Earth is 81 times more massive than the Moon).
3. The center of mass between the Moon and the Earth is located about 1700km
beneath the surface of the Earth, a very strong bias towards the Earth considering
the distance between both bodies.
4. The average density of the Moon is 3300 kg/m^3, much less than the average desity
of the Earth, which is 5500 kg/m^3.
5. There are significant differences in the chemical composition between both bodies
due to their difference in density.
6. Without compression, which is the extent to which the interior of the body is
compressed by the weight of overlying material, the Moon’s density would be
reduced to 3200 kg/m^3 (which is about 70% of the uncompressed density of the
Earth).
7. The Moon’s density is the same as the crustal rocks of the Earth.
8. The Moon likely has a partially molten metallic core between 440 and 700 km
across, which is about 13% to 20% of the Moon’s diameter and 2% to 3% of the
Moon’s mass.
9. In contrast to the Moon’s core, the Earth’s core occupies about 55% of the Earth’s
diameter and makes about ⅓ of the Earth’s mass.
10. Four seismometers were placed on the Moon during the Apollo missions, recording
thousands of mild quakes but none exceeded 2 on the Richter scale.
11. Lack of strong Moonquakes shows that the Moon’s interior is inactivecompared with
that of Earth.
12. Analysis of the speeds of the seismic waves suggest that the crust is 65 to 150 km
thick, which is much thicker than the Earth’s crust.
13. The Moon’s lithosphere extends to about 1000 km beneath its surface, where
beyond that it becomes partially molten.
Section 9.7
1. Fission theory is the moon was once part of the earth but it broke away because of
the rapid rotation of the earth.
2. One Problem with the fission theory is that the parts flung outward would be along
the equator where the speed of rotation is the fastest.
3. Another problem is explaining why the earth was rotating fast enough to have spun
off the moon.
4. the earth has an iron core that makes up about 32% of its mass
5. Binary accretion theory: the moon formed while in orbit of earth but is not made from
the same material from earth.
6. It was formed by the same cloud material, which is why they have the same
composition. this is known as the double planet theory.
7. Problem is that it doesn’t explain the abundance of iron in the earth, but not the
moon.
8. Capture theory: when the moon formed outside of earth's orbit but in the inner solar
system, but after almost having a collision, earths gravity was able to pull the moon
into orbit.
9. Problem is that the moon would approach the earth too quickly for the earth to slow it
down enough to pull it into orbit, and would cause a collision.
10. another problem is that if the moon was formed elsewhere, there wouldn't be an
explanation why the two compositions would be so similar.
11. Giant Impact theory: when a body about the size of mars hit the earth, then the
debris from the impact was then formed into the moon while in orbit, thus creating
the moon.