Science 9: Unit E: Space Exploration

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Science 9 Unit E Space Exploration

• Topic 1 For Our Eyes Only

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A Brief History of the Universe

• The Ancient Greeks
• The Ancient Greeks believed that the universe was
  split into two parts the imperfect Earth and the
  prefect, unblemished sky made up of the sun,
  moon, stars, and five planets.

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Ancient Greeks Contd

• The Greeks believed that the sun was actually
  their god Apollo riding in a fiery chariot. To
  help make sure the sun rose up everyday you had
  to pray to Apollo and offer sacrifice. Events
  such as a solar eclipse were interpreted that the
  Greeks had offended Apollo somehow.
• Everything worked like clockwork in the sky
  except for the five planets, which didnt follow
  any pattern. Sometimes the planets rose at night
  other times in the morning, sometimes they moved
  left, other times they moved right. The Greeks
  just assumed that the planters were special and
  gave them the names of their gods Mercury,
  Venus, Mars, Jupiter, and Saturn. Planet means
  wanderer in Greek.

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Geocentric Model

• Means Earth-centred.
• Eventually the idea that the sun was a chariot
  for Apollo became offensive and silly to the
  Greeks and Romans, so a new, more scientific
  model was created, the Geocentric Model.
• The Geocentric Model is made of the following
  ideas
• 1. The Earth was the center of the universe.
  Everything orbited the Earth.
• 2. The sun, moon, and planets moved around the
  Earth because they were attached to invisible
  shells, which turned around the Earth pulling the
  objects with them.
• 3. The planets were special because their
  movements changed over time. They changed
  direction and speed in the sky so they were given
  epicycles little circles that they would spin
  around while still being attached to their
  invisible shells.

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Geocentric Model
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Geocentric Model

• This model nearly perfectly explained how and why
  everything moved in the sky. People were
  satisfied with this model even though it was
  complicated. It lasted over 1500 years with no
  problems. It became the accepted model for the
  Western World.

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The Heliocentric Model

• Means sun-centred
• In the early 1500s a Polish priest, Nicholas
  Copernicus, created a new model which put the sun
  at the center of the universe and made the Earth
  a planet orbiting the sun. This model was called
  the Heliocentric Model. This was very
  controversial and not very well accepted by the
  Catholic Church.
• 100 years later, Italian scientist Galileo used
  telescopes to study the moon and planets. He
  discovered that the moon is not perfect, but full
  of craters and ridges, so the perfect heavens
  were not so perfect after all.

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Heliocentric Model Contd

• Galileo also discovered five moons orbiting
  around Jupiter. This was the first proof of
  something NOT orbiting around the Earth. This
  made the Heliocentric model more believable and
  accepted.

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Heliocentric Model