The Solar System

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The Solar System

• Section 3 The Inner Planets

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Guide For Reading

• What are the main characteristics of the inner
  planets?

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The four inner planets are called the ________
planets.

• terrestrial planets

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This name comes from the latin word _____
meaning ______.

• terra
• Earth

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The names of these planets are _____, _____,
____, ______.

• Mercury
• Venus
• Earth
• Mars

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Guide For Reading What are the main
characteristics of the inner planets?

• The four inner planets are small and have rocky
  surfaces
• Mercury, Venus, Earth, Mars are known as the
  terrestrial planets

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Earth
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What three gases primarily make up Earths
atmosphere?

• Oxygen
• Nitrogen
• Carbon dioxide

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Earth is made up of ______ water.

• 70

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Figure 11 Interpreting DiagramsWhat are Earths
three main layers?

• Crust
• Mantle
• Core (Inner Outer)

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How do scientists use Earth to learn about other
planets? (Give an example)

• Scientists use what they know about Earth to make
  inferences about the other planets
• Example When astronomers find volcanoes on other
  planets, they infer that these planets have once
  had hot material inside them

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Planet Facts (Earth)

• 70 covered with water
• Oxygen makes up 20 of Earths atmospheric gas
• Suitable for life
• Has 1 moon

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Mercury
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Mercurys interior is mainly made up of dense
metals, ________ and _______.

• iron
• nickel

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Why cant people on Earth get a good view of
Mercury?

• Because Mercury is so close to the sun, people on
  Earth can not get a good view of it

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The space probe named _______ was launched in
_______ and only photographed _______ of
Mercurys surface.

• Mariner 10
• 1974
• Half

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What did this space probe discover about the
surface of Mercury?

• The Mariner 10 found that Mercury has many flat
  plains and many craters on its surface

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Mercury has an extremely _________ atmosphere.

• Thin

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Why is Mercury considered to be a planet of
extremes?

• Mercury has the greatest temperature range in the
  solar system
• During the day, the side facing the sun reaches
  temperatures of 450C
• Because Mercury has almost no atmosphere, at
  night all the heat escapes into space and the
  temperature drops to -170 C

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Checkpoint Why is it difficult for astronomers
to learn about Mercury?

• Mercury is so close to the sun that it is
  difficult for astronomers on Earth to get a good
  view of it.

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Planet Facts (Mercury)

• Greatest temperature range
• Extremely thin atmosphere
• So close to the sun that it is difficult for
  astronomers to get a good view
• 59 Earth days to rotate (1 rotation 59 Earth
  rotations)
• ¼ Earth years to revolve (1 Earth revolution 4
  Mercury revolutions)

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Venus
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Venus is often called the ______ _____ because it
rises before the sun.

• Morning Star

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Why is Venus often referred to as Earths twin?

• Venus id often referred to as Earths twin
  because they are similar in
• Size
• Density
• Internal structure

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Why is Venus day longer than its year?

• Venus day is longer than its year because it
  takes 8 months to rotate (day), and 7.5 months to
  revolve (year)

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Retrograde Rotation

• The spinning motion of a planet from east to
  west, opposite to the direction of rotation of
  most planets and moons

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Describe the hypothesis astronomers use to
explain Venus retrograde rotation.

• Venus was struck by a very large object billions
  of years ago
• This collision cause the direction of its
  rotation to change

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Venus ______ atmosphere prevents Venus from ever
having a sunny day.

• Thick (cloudy)

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Why can you not breath on Venus?

• Venus atmosphere is mostly carbon dioxide

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Greenhouse Effect

• The trapping of heat by a planets atmosphere

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Checkpoint Why is the surface of Venus so hot?

• The surface of Venus is so hot because carbon
  dioxide traps heat inside the atmosphere.
• This is called the greenhouse effect

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Planet Facts (Venus)

• Day is longer than a year (rotates at a slower
  rate than it revolves)
• Retrograde rotation (Rotates east to west
  opposite the other planets)
• Atmosphere is so thick it causes the greenhouse
  effect

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Mars
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Why is Mars called the Red planet?

• When Mars is viewed in the sky, it has a slightly
  reddish tinge

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The atmosphere of Mars is mostly _________.

• carbon dioxide

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Mars has a _______ _______ at its North Pole.

• polar
• ice cap

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The ice cap on Mars north pole is not water, but
rather ______.

• Carbon dioxide

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Why does Mars have seasons? How do they vary?

• Mars has seasons because of the slightly tilted
  axis (like Earth)

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What geological feature that is found on Earth
can be also found on the surface of Mars?

• Volcanoes
• Olympus Mons (shield volcano) is the largest
  volcano in the solar system
• 17 miles tall 320 miles across

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Mars has two small moons, ________ and ________
that are covered with craters.

• Phobos

• Deimos

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Planet Facts (Mars)

• Called the red planet because of its dust color
• Frozen ice caps with a layer of frozen carbon
  dioxide
• Has two moons

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