The origins of the Universe

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• The origins of the Universe
• The Earth is part of a Solar System.
• The Solar System is centred on the sun.
• The Solar System is also made up of nine
  planets, 60 moons (1978 - we thought 42 moons),
  thousands of minor planets or asteroids, hundreds
  of comets and millions of meteors.

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• The Solar System is a small part of a group of
  millions of stars called a Galaxy.
• This Galaxy is called the Milky Way.
• This Milky Way is one of millions of other
  Galaxies in the Universe.

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• People who study the Universe are called
  Astronomers. In the study of the HEAVENS
  (Astronomy) -- many names came up through History
  . The following are a list of famous
  Astronomers
• ARISTARCHUS (Greek) (310 - 230 B.C.)
• PTOLENMY (140 A.D.)
• COPERNICUS (1473 - 1543)
• TYCHO BRAHE (1546 - 1601)
• KEPLER (1571 - 1630)
• GALILEO GALILEI (1564 - 1642)
• ISAAC NEWTON (1642 - 1727)

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• Time does not permit us to study each ones
  accomplishments, but for the origins of the
  Universe and the Solar System, two other
  Astronomers must be looked at
• PIERRE DE LAPLACE (1796)
• G. P. KUIPER
• There are four theories to the origin of the
  Universe and our Solar System

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• 1) Nebular Hypothesis (created by Pierre De
  LaPlace)
• Pierre De LaPlace imagined a globe of hot,
  glowing gases in space, rotating slowly. This
  globe due to its rotation contracted (Centripetal
  Force). As the globe contracted, it rotated
  faster.
• The faster rotation caused the globe to flatten
  out into a disc.
• As it shrank, this left rings of gas around it.
  Diagram A on the next slide.
• These rings separately began to rotate and
  revolve. These rings eventually contracted to
  form the solid planets. Diagram B on the next
  slide.

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A
Planet Earth by Gary Birchall and John
McCutcheon, (John Wiley and Sons)
B
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• 2) Proto Planets (created by G.P. Kuiper)
• G.P. Kuiper suggested that rather than rings,
  big chunks of gas were left behind.
• These chunks or clouds were called Proto
  Planets.
• Because of their mass and gravitational pull,
  these chunks of gas began to spin around one
  another. The bigger chunks attracted smaller
  pieces. These proto-planets condensed to form
  planets and moons. See the diagram on the next
  slide.

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Planet Earth by Gary Birchall and John
McCutcheon, (John Wiley and Sons)
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• 3) Dualistic Theory
• This theory states that the sun was once a very
  large star and that either of the two following
  scenarios occurred
• a) Another star was once very close to the sun
  and it eventually blew up (went super nova). The
  explosion threw out debris. This debris created
  the planets. Diagram A on the next slide.
• b) Another star came very close to our sun. The
  gravitational pull of this other star tore chunks
  out of our sun. These chunks eventually became
  the planets. The star then moved on through the
  Universe. Diagram B on the next slide.

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A
B
Exploring the Universe by Mitchell Beazley
Encyclopaedias
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• 4) Big Bang Theory (created by group of
  astronomers)
• This theory states that the universe began
  approximately 15 to 20 billion years ago when a
  big ball of gas (from a giant cloud) ripped apart
  in a big bang. It is the most widely accepted
  theory.
• As this big bang or explosion occurred, chunks
  of gas were left behind from the centre of the
  explosion outwards.
• This gas clustered together (centripetal force)
  and this began the formation of the planets,
  stars and galaxies. Diagram A on the next slide.
• Diagram B takes the theory a step further. It
  illustrates that the Universe will eventually
  reach a point where it will begin to contract and
  close in on itself eventually exploding again and
  starting the process all over again.

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A
Exploring the Universe by Mitchell Beazley
Encyclopaedias
B
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• Years ago the Big Bang Theory was just a
  hypothesis. In other words, it had no facts or
  evidence to back it up. But in the early 1900s
  astronomers started to find evidence that pointed
  to a Big Bang.
• In 1922, astronomer Edwin Hubble observed that
  the universe was expanding. The most distant
  galaxies he could see through his telescope were
  moving away at about 40 000 km per second.
• This observation led to what is now called
  Hubbles Law, which states that the velocity at
  which a galaxy is moving away from us is
  proportional to the distance of the galaxy from
  us. That is if galaxy B is twice as far away as
  galaxy A, it is receding twice as fast as galaxy
  A.

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• Wow, imagine the Universe is expanding. Where is
  it going?
• Albert Einstein hypothesized that the Universe
  began as a small Cosmic Egg the size of the
  head of a needle perhaps? This egg exploded with
  such force that the fragments are still flying
  out from the center of the explosion.
• Russian physicist George Gamow in the 1940s
  first coined the term Big Bang when he
  hypothesized that the radiation accompanying the
  explosion should still exist as radio waves.
• In 1964 two physicists found this radio-wave
  radiation.
• Based on what we have learned about the
  expanding universe, it is conceivable that we can
  actually see in the past. Light travels at a
  speed of 299 792 km per second. A light year is
  the distance light travels in one year (approx.
  9.5 trillion km).

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• So, if we look at a star one light year away,
  the light we would see would have been created a
  year earlier. The closest star to our solar
  system is Proxima Centauri. It is 4.3 light years
  away (40X1012 km). How far in the past would you
  be seeing if you viewed this star?
• Most stars are further than Proxima Centauri.
  Stars in our galaxy are as far as 80 000 light
  years from the sun. Stars in distant galaxies are
  billions of light years away. If the universe was
  created 15 billion years ago, light created when
  the universe was born may still be seen today!

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The many galaxies in our universe.
Our galaxy - The Milky Way - looks like this (It
is a Spiral Galaxy)
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THE END!