Our Moon and other Moons in the Solar system – Our Moon
What is a moon?
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A moon is a _____________ ______________ of a planet or dwarf planet
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There are over __________ moons around the planets and dwarf planets in our solar system
Number of moons around each planet:
Planet
Number of known moons
Mercury
______
Venus
______
Earth
______
Mars
______
Jupiter
______
Saturn
______
Uranus
______
Neptune
______
Dwarf planet
Pluto
______
Eris
______
How do we explain the existence of our Moon?
The Giant Impact theory:
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Between 4.4 and 5 billion years ago an object about the size of _____________ struck a very
young Earth and blasted material into orbit around Earth
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The “youngest” Moon rocks are _______________________ years old
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The material from the collision came together by gravity (called _____________) and became
our Moon.
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The Moon was _________ ___________ to the Earth when it first formed
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It was between ______ - _______ miles away
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Now it is 240,000 miles away and _________ _________ from us by 1.5 inches/year
Why does the Moon look the way it does?
Impact Cratering
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Most cratering happened soon after the solar system formed – “_________________________”
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Craters are about _______________ wider than object that made them.
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Small craters ____________ ______________ large ones.
Why does the Moon look the way it does? (Cont.)
Volcanism
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Volcanism happens when molten rock (magma) finds a path through the ____________
_____________ (lithosphere) to the surface.
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Molten rock is called ____________ after it reaches the surface.
The Lunar Maria were formed by volcanism
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Smooth, dark lunar maria are __________________________________ than lunar highlands.
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Maria were made by floods of ___________ __________.
The Moon is geologically dead
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Moon is considered geologically “dead” because geological processes have virtually _________.
Do the Moon and Mercury have any atmosphere?
Exospheres of the Moon and Mercury
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Sensitive measurements show that the Moon and Mercury have virtually
___________________________.
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The little gas there comes from _________ and the __________ __________ that eject surface
atoms.
The Moon’s surface conditions
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No atmosphere
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No _________ water – frozen water at the ____________
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Because of the lack of an atmosphere the moon experiences ____________ ________________
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Daytime = 130C (265°F)
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Nighttime = -190C (-310 F)
The moon has 1/6th of Earth’s ____________________
Our Moon and other Moons in the Solar system – moons around other planets
What kinds of moons orbit the other planets of the solar system?
Small moons
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These are far more ________________ than the medium and large moons.
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They do not have enough gravity to be spherical: Most are “___________________________.”
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They are captured _______________ or ______________, so their orbits do not follow usual
patterns.
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Mars has two moons that are thought to be captured asteroids from the asteroid belt
Medium and Large Moons
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Enough self-gravity to be _______________
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Often have substantial amounts of ___________
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Except for our Moon they formed in orbit around ____________ ___________ (gas giants)
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Circular orbits in __________ _____________ as planet rotation
Jupiter’s Galilean moons
Io
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Io is the most volcanically active body in the solar system
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Volcanic eruptions continue to change Io’s surface.
Europa
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The effects of gravity crack Europa’s surface ice.
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Europa’s interior also warmed by tidal heating producing a possible ocean under the ice.
Ganymede
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Largest moon in the solar system
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Clear evidence of geological activity
Calisto
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“Classic” cratered iceball
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No evidence of geologic activity
Other interesting moons in the solar system
Titan
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Saturn’s largest moon Titan is the only moon in the solar system to have a thick _____________.
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It consists mostly of nitrogen with some argon, methane, and ethane.
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Huygens probe provided first look at Titan’s surface in early 2005.
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It found liquid methane and “rocks” made of ice.
Enceladus
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Enceladus is a medium sized moon of Saturn
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Ice fountains of Enceladus suggest it may have a _______________ _____________.
Triton
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Neptune’s largest moon Triton is similar to Pluto, but larger
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Also shows evidence of past geological activity
Charon
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The largest moon of Pluto is also the largest moon relative to the size of its planet
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Charon is ½ the size of Pluto, and is thought to be ________________________ like Pluto as well
Top 12 largest moons in the solar system
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