LUNAR FORMATION
TABLE OF CONTENTS
Image from NASA
TABLE OF CONTENTS
• What is Lunar Formation?
• Formation Theories
• Giant Impact Theory
• Links
Earth’s Moon
LUNAR FORMATION
WHAT IS LUNAR FORMATION?
Image from NASA
• Lunar formation is the
process in which a
moon is created.
• There are several
theories on how
Earth’s moon was
formed, but nobody is
sure what really
happened.
Earth’s Moon from South Pole
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LUNAR FORMATION
FORMATION THEORIES
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Image from NASA
• There are four main
theories of lunar formation:
• Fission Theory: The moon
was part of the Earth, but
somehow broke off and
became its own celestial
body.
• Capture Theory: The
moon, which was formed
elsewhere, traveled
through Earth’s orbit and
got caught in its gravity
field.
Earth’s Moon
More Theories
LUNAR FORMATION
Image from NASA
MORE FORMATION THEORIES
Earth and its Moon
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• Condensation Theory:
Both the Earth and the
moon formed at the
same time in the same
area.
• Giant Impact Theory:
The dominant theory in
which a large celestial
body slammed into the
Earth. The moon was
created out of the
debris.
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LUNAR FORMATION
GIANT IMPACT THEORY
• The Giant Impact
Theory, also known as
the “Big Whack,” is the
dominant lunar
formation theory.
• In this theory, a Marssized “protoplanet”
collided with Earth,
releasing debris which
eventually formed the
moon.
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Artist’s interpretation of the impact.
More on Giant Impact Theory
LUNAR FORMATION
MORE GIANT IMPACT THEORY
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Image from ClassZone
• At first, the theory was
heavily criticized, but
with the development of
models and simulations,
the theory became more
widely accepted.
• Since a collision on this
scale is hard to model,
computer simulations
have been used to try to
replicate the event.
Screenshot from a Giant Impact
simulation. Click the image to view the
animation.
Giant Impact Theory’s Issues
LUNAR FORMATION
Image from DTA
GIANT IMPACT ISSUES
Simulated image of the moon’s accretion.
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• No simulation has yet
been able to confirm the
theory. Often in
simulations, the Earth
after collision is left
spinning too fast or its
mass is decreased by too
much.
• The theory does not
explain the Moon’s lack of
iron and siderophilic (ironliking) elements.
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LUNAR FORMATION
LINKS
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Image from NASA
• http://www.swri.org/3p
ubs/ttoday/spring99/m
oon.htm
• http://www.classzone.
com/books/earth_scie
nce/terc/content/visual
izations/es2501/es250
1page01.cfm?chapter
_no=visualization
False Color Image of the Moon