Download Astro ch 3

Lunar Geology
1. Internal Layers
2. Seismometer Data
http://www.psi.edu/node/5657
3. Prospector Data
4. Possible Origins
5. Major Surface
Features
6. Miscellaneous Facts!
http://www.psi.edu/node/5657
Internal Layers, Seismometer Data, and
Prospector Data
Crust 65 km
Mantle 950 km
Core 200 km
Seismometers were
deployed at Apollo 11, 12, 14,
15 and 16 landing sites.
Transmissions were
received until 1977.
Buzz Aldrin – Sea of
Tranquility
The Lunar Prospector was launched January 1998.
The onboard magnetometer and Doppler
Gravity Detector provided additional data of the Moon’s
interior and supported seismometer data.
Earth’s and Moon’s Internal Layers
Earth’s and Moon’s Internal Layers
Moon Layers
• Crust
– Dry, dusty, rocky
– Thicker on the far side than the near side
– Rocks formed 4.3 billion years ago
• Rigid Lithospheric Mantle
– Not hot enough to flow
• Nonrigid Asthenospheric Mantle
– Only the deepest parts are hot enough to flow
• Core
– Iron rich, but does not generate much of a
magnetic field
How Much Would I Weigh On The
Moon???
• The moon’s gravitational pull is one
sixth of the gravitational pull you
experience on Earth.
• Calculate your weight on the moon.
• Calculate your mass on the moon.
Moon Formation Theories
Theory 1: Capture
• The moon formed elsewhere in
the solar system, then was
captured into Earth’s orbit.
• Capture into the moon's present
orbit is very improbable.
• Something would have had to
slow the moon down by just the
right amount at just the right time.
Theory 2: Co-Formation
• The moon formed in orbit about
the Earth via accretion.
• If the moon formed in the
vicinity of the Earth, it should
have nearly the same
composition -- specifically a large
iron core.
Theory 3: Fission
• A rapidly spinning Earth could have
cast off the moon from its outer
layers.
• The Earth-Moon system does not
contain evidence of this rapid spin.
• All of these hypotheses do not
address the extra baking that lunar
material has received.
Theory 4: Catastrophic Collision
A crazy theory that actually works!
• A Mars-sized object (name???) struck Earth, exploding
the outer layers of both objects. The moon formed from this
ejected material.
• Catastrophic collisions were common in the early stages of
the solar system.
• Computer models show that a collision at a certain speed
and angle will produce the right amount of debris in Earth’s
orbit.
• Today, this scenario is widely accepted.
http://www.youtube.com/watch?v=c0FCE4H0Dro
Major Surface Features
Entire surface
is covered with
craters
Dark circular
regions are
called maria
or lunar seas
Lighter surface
areas are
called lunar
highlands
Dark color was caused by meteor impacts that created lava
flows and formed basalt
Water on the Moon
• Meteorites may have
transferred water to the
moon.
• Ice may be present in the
permanently dark craters at
either lunar pole.
• 650 square miles at each
pole, totaling 6.6 billion
tons.
Water on the Moon
• Why do we care about water on the
moon?
– Ice’s presence helps narrow models of
moon formation and early solar system
activity.
– Shipping water to the moon for human use
would be expensive (at least $2000/kg).
– Water could be converted into breathable
oxygen and rocket fuel.
http://www.youtube.com/watch?v=YrLuOFoPlRc
Lifeforms on the Moon
• Hints of microbial life have been found, but no
distinctive evidence has surfaced.
• The moon is too hostile to support life.
– Very thin atmosphere of Ne, He, H, Ar, Na, K.
– Temperatures fluctuate between -173°C during
the night and 125°C during the day.
• Fossil evidence may have been transferred to
the moon from Earth by meteorite impacts.
http://www.youtube.com/watch?v=H2xaFLR0V4k
What Have We Found on the Moon?
• Lunar rocks and soil
– More than 800 pounds have been collected
and returned to Earth.
– Most are found in the Johnson Space
Center in Houston.
– It is illegal for a private individual to own a
lunar rock!
Miscellaneous Facts
• Where did the moon get its name?
– “Moon” came from the Old Norse mani, the
Greek mene, or the Latin mensis (month).
• How big is the moon?
– 2,159 miles in diameter, 8.1x1019 tons
• How far away is the moon from Earth?
– 238,857 miles on average.
• Why is the moon round?
– Due to its rotation and gravity.
• How long is a day on the moon?
– The moon’s day is the same as its year: 27.3
Earth days.
• What is the “dark
side” of the moon?
Have we ever gone
there?
– Due to tidal locking,
the same side of the
moon always faces us.
– Both sides can be light
OR dark, depending
on where the moon is
in its revolution around
Earth.
• What is the “dark
side” of the moon?
Have we ever gone
there?
– So…“dark side” of
the moon is an
inaccurate term.
More descriptive
terms are “far side”
and “near side” of
the moon.
– We have walked on
the near side of the
moon and have
photographed the far
side of the moon.
http://www.youtube.com/watch?v=OZIB_leg75Q