The Earth and Beyond

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The Earth and Beyond
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Contents

• The Solar System
• Stars
• Solar Systems, Galaxies the Universe
• Comets
• Life Cycle of Stars
• Red-Shift
• History of the Universe
• Future of the Universe
• SETI

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The Solar System
My Very Efficient Mind Just Stores Up Nine Planets
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Stars

• Stars are burning balls of gas e.g. our Sun
• Stars give out light
• This light reflects off planets so we can see
  them
• Planets are much smaller than stars
• but they seem much bigger as they are much
  closer
• The 9 planets orbit the sun, Earth orbits the Sun
  once a year

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Stars

• Stars are burning balls of gas e.g. our Sun
• Stars give out light
• This light reflects off planets so we can see
  them
• Planets are much smaller than stars
• but they seem much bigger as they are much
  closer
• The 9 planets orbit the sun, Earth orbits the Sun
  once a year

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Solar Systems, Galaxies the Universe
Our Sun is one of millions of stars that orbit
the centre of the Universe
The Milky Way is one of more than a billion
galaxies in the Universe
The Universe is expanding
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Comets

• Comets appear every few years
• Comets have highly elliptical orbits around the
  Sun
• Comets are visible when they are close to the Sun
• A comets orbit is fastest near the Sun due to
  the Suns gravity. It slows as it moves further
  away from the Sun

Tail is pushed away from sun by solar pressure
Tail is made of ice and rock
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Life Cycle of Stars
cools and contracts
Layers of dust gas are ejected
clouds of dust gas
H?He heat light ejected?star
H runs out?swells red cooler
dense core neutron star
explode? supernova
or black hole (crushes atoms!)
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Red-Shift

• Light from distant galaxies is shifted towards
  the red end of the spectrum
• Frequencies become lower as they move away (like
  the Doppler Effect for sound)
• Further away greater red-shift
• Universe is expanding
• Also evidence from microwave
• radiation (background radiation)
• that Universe is cooling

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History of the Universe

• 1. Steady State Theory
• Universe has always existed
• and Universe will always exist
• No convincing evidence
• Not much support for the Steady State Theory

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History of the Universe

• 2. Big Bang Theory
• Universe was compressed and exploded Big Bang
• Occurred 15 billion years ago
• Estimated by current rate of expansion
• Expansion is slowing due to gravity

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Future of the Universe

• According to the Big Bang Theory
• 1. Expand Forever
• If too little mass for gravity to stop expansion
• Universe will expand and spread out into eternity
• 2. Big Crunch
• If enough mass to stop expansion, universe will
  contract
• Big Crunch!
• Big Crunch would produce another Big Bang and so
  on!

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SETI
Scientists search for extra terrestrial
intelligence

• Radio Signals
• SETI looks for radio wavelength signals being
  sent to Earth
• These signals can only be sent by a transmitter
• SETI has been running for 40 years not found
  anything
• Now searching for laser signals too!
• Robots Collect Photos and Samples
• Spacecraft are sent to planets to look for
  microorganisms
• Collect samples and take photos
• Scientists analyse samples and look for fossils
  etc.

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Summary

• Solar system 9 planets 1 star
• Stars emit light, planets reflect this light
• Solar systems are in galaxies which are in the
  Universe
• Comets (rock and ice) have long elliptical orbits
  around Sun
• Life cycle of stars differs for massive small
  stars
• Red-shift evidence for fast expansion of
  galaxies
• History of the Universe Big Bang or Steady
  State
• Future of the Universe Big Crunch or Eternal
  Expansion
• SETI Radio signals, laser signals, collect
  photos samples