Moons

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Moons

• The satellites of the solar system

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Moons of our solar system

• As of July 2009, there are 336 known natural
  moons in our solar system. 168 moons orbit the
  "full-size" planets (Earth, Mars, Jupiter,
  Saturn, Uranus, and Neptune), while 6 moons orbit
  the smaller "dwarf planets" (Ceres, Pluto,
  Haumea, Makemake, and Eris). Others orbit
  asteroids and Trans-Neptunian objects.
• Mercury and Venus have no moons

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Which planet? How many?

• Earth 1 moon Luna
• Mars 2 moons
• Jupiter 63 moons
• Saturn 62 moons
• Uranus 27 moons
• Neptune 13 moons
• Pluto 3 moons
• Haumea 2 moons
• Eris 1 moon

• When we consider that Saturn could have as many
  as 1 million moons, the question arises, What
  constitutes a moon?

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What is a moon?

• A moon is a natural satellite of a celestial
  body. It can orbit a planet, an asteroid, etc.
• Usually a moon orbits either a planet or a dwarf
  planet
• The official size of a moon is still being
  debated and it does not appear that it will be
  settled soon.

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Ten largest moons in the solar system

1. Ganymede - Jupiter - 5268 kilometers in diameter
2. Titan - Saturn - 5150 kilometers in diameter
3. Callisto - Jupiter - 4806 kilometers in diameter
4. Io - Jupiter - 3636 kilometers in diameter
5. Moon - Earth - 3474 kilometers in diameter
6. Europa - Jupiter - 3122 kilometers in diameter
7. Triton - Neptune - 2706 kilometers in diameter
8. Titania - Uranus - 1578 kilometers in diameter
9. Rhea - Saturn - 1528 kilometers in diameter
10. Oberon - Uranus - 1523 kilometers in diameter

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Oddball moons

• Triton travels around Neptune backwards and could
  be a captured body from the Kuiper Belt. In fact,
  Triton may look a lot like Pluto.
• Titan, the second largest moon in the solar
  system, is an icebox Earth, with a thick
  atmosphere, methane meteorology, and youthful
  surface.
• Ganymedes icy mantle could contain a liquid
  ocean layer, but evidence for that is not
  conclusive.

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Which is the largest moon in the solar system?

1. Luna
2. Ganymede
3. Titan
4. Triton

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The planet with the most moons is

1. Saturn
2. Jupiter
3. Neptune
4. Venus

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A moon is.

1. Anything that orbits a celestial body thats
   bigger than a breadbox
2. a natural satellite of a celestial body
3. Bigger than a truck
4. A natural satellite of a celestial body that
   orbits a planet in the same direction as the
   planets rotation

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The moon that orbits its planet in the direction
opposite the planets rotation is

1. Ganymede
2. Io
3. Triton
4. Titan

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How do we know what we know about the moons?

• Mariner 1-10 1962 to 1973
• Pioneer 10 and 11 1972 and 1973
• Voyager 1 2 1977
• Galileo 1989
• Cassini - 1997
• LRO (Lunar Reconnaissance Orbiter) - 2009
• Hubble (1990) and Kepler (2009)

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Luna the Earths moon
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Luna

• The Earths only natural satellite
• Second brightest object in our sky
• Albedo of Luna is .07 (reflects 7 of the light
  that hits it), surface is color of charcoal
• Fifth largest satellite in the solar system
• 1/4th the diameter of the Earth
• 1/81st of the Earths mass
• Synchronous rotation with the Earth we always
  see the same side of the moon

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The two sides of the moon
The side we always see
The dark side of the moon
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Actually we see more than we know

• Due to the lunar libration, or a slow rocking
  back and forth motion, we actually see about 59
  of Lunas surface on the side that faces us.

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The side hardly anyone sees

• Taken by Clementine spacecraft, this is a mosaic
  picture of the south pole of Luna

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What we see changes

• What we see depends on the phase of the moon from
  the sliver of a new moon to a full moon when the
  moon is behind us, reflecting the Suns light

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What we see also depends on how close Luna is to
the Earth
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What is the cause of the rocking back and forth
motion?

• May be due to extended influence of Earths
  gravity on the moon while it is retreating from
  the Earth
• Moons core is actually off-center

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What are the numbers?

• Moon Numbers Size 3,476.2 kilometers -- 0.2725
  Earths -- 14th largest solar system body Orbit
  384,400 kilometers from Earth Calendar 1 lunar
  day 29.53 Earth days
• Our Moon is retreating (moving away) at about 3.8
  centimeters (1.5 inches) per year.

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Our moon orbits the Earth

1. 24,000 km away.
2. 384,000 km away.
3. Whenever it feels like it.
4. Every couple of months or so.

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Luna is the ________ largest satellite in the
solar system.

• Second
• Third
• Fourth
• Fifth

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Internal structure of our Moon

• Geologically distinct mantle, crust and core
• Solid inner core is probably high in iron content
  approximately 240 km in diameter
• Liquid iron outer core and an area of partially
  melted boundary between core and mantle

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Crust

• The dark, featureless areas are called maria,
  thought by early observers to be seas on the
  surface
• Mare are solidified pools of basaltic lava
• Maria are found almost exclusively on the side
  facing the Earth and make up 31 of the surface
• Lighter colored regions, terrae, are highlands
• It is not made of cheesesorry
• Neither is there a man in the moon

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Where did it come from?

• Three traditional theories
• Moon and Earth developed at the same time
  (condensation hypothesis)
• Moon was made of material that came from the
  Earth (fission hypothesis)
• Moon was captured by the Earths gravity (capture
  hypothesis)

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Large-impact hypothesis

• Large celestial body struck the Earth in its
  early stages
• Most of the iron merged with Earth and
  differentiated into the core
• Most iron poor debris formed a ring around Earth
  that accreted into Luna
• Evidence? Composition of lunar rocks, signs of
  intense heat,