I. Expanding Universe

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I. Expanding Universe

• A. How the Universe was Formed
• 1. Theory the universe began 13.7 billion years
  ago.
• 2. No bigger than a period at the end of the
  sentence.
• 3. Explosion called the BIG BANG.
• a) According to theory, formed in an instant.
• b) in an enormous explosion

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I. Expanding Universe

• B. cooled as universe expanded.
• 1. if theory correct should find universe still
  expanding
• 2. Energy still being given off.
• C. Atoms began to form a few hundred thousand
  years later
• D. 200 million years after that stars and
  galaxies began to form
• E. Galaxies on the move.
• 1. A Galaxy is a series of star groups
• a). Different kinds of galaxies
• (1)spiral
• (2)elliptical
• (3)irregular galaxies

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I. Expanding Universe

• b) Spiral have huge spiral arms, we are part of
  these
• c) Elliptical
• (1)have little dust and gas
• (2)contain older stars
• d) irregular have not order or shape
• e) less common than spiral and elliptical

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I. Expanding Universe

• 2. Edwin Hubble
• a) Studied the spectrum or energy
• b) Found that he could tell how fast the galaxy
  is moving
• c) If the galaxy is moving toward our galaxy or
  away
• d) Found a relationship between the distance to a
  galaxy and its speed.
• e) Came up with HUBBLES LAW The farther away a
  galaxy is, the faster is moving away from us.
  This law supports the Big Bang Theory.

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I. Expanding Universe

• F. Cosmic Background Radiation
• 1. 1965 Arno Penzias and Robert Wilson
  accidentally detected faint radiation on a radio
  telescope (next slide)
• 2. Came from all directions in space.
• 3. Determined to be the leftover thermal energy
  from the big bang.

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I. Expanding Universe

• G. Universe age
• 1. using cosmic background radiation
• 2. Hubbles Law
• 3. universe is about 13.7 billion years old.

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II. Formation of the Solar System.

• A. After the big bang, matter separated into
  galaxies.
• B. Solar Nebula was created
• 1. A giant cloud of gas and dust collapsed to for
  our solar system or solar nebula
• 2. Gravity pulled the nebula together.
• 3. as it shrank inward spun faster and faster
  flattening forming a rotating disk

CONE NEBULA
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II. Formation of the Solar System.

• 4. most of the gas was pulled into the center
• 5. gas became hot and dense enough for nuclear
  fusion to begin
• 6. THE SUN WAS BORN!

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II. Formation of the Solar System.

• C. Planetesimals
• 1. Outer part of spinning disk, gas and dust
  formed asteroid-like bodies called Planetesimals.
• 2. These created the building blocks for the
  planets.
• 3. The Planetesimals collided and grew bigger
  sticking together eventually forming the planets.

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II. Formation of the Solar System

• D. Inner Planets
• 1. The solar system was extremely hot when
  forming
• 2. because of this most water and ice-forming
  material vaporized being so close to the sun
• 3. Mercury, Venus, Earth, and Mars are all
  relatively small and rocky

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II. Formation of the Solar System

• E. Outer Planets
• 1. further out from the sun, much cooler
• 2. Greater amount of gravity
• 3. planets were able to increase in size because
  they were able to obtain the following gasses
• a) hydrogen
• b) helium
• 4. Planets like Jupiter, Saturn, Uranus and
  Neptune became very large as well as made of gas
  and ice

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The Future of the Universe

• A. One possibly the universe will expand
• 1. will continue to do so
• 2. all stars will burn out
• B. Another possibility is the universe will begin
  to move inward
• 1. the universe will become cold and dark
• 2. A reverse big bang or big crunch
• 3. all matter will be crushed into an enormous
  black hole

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The Future of the Universe

• A. New observations indicated that the expansion
  is more likely to happen.
• B. Dark Matter
• 1. makes up about 23 of the universes mass
• 2. can not be seen directly
• 3. can be inferred by observing the effect of its
  gravity on visible objects such as stars or light
• 4. discovered by Vera Rubin

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The Future of the Universe

• E. Accelerating Expansion
• 1. late 1990s astronomers observed the expansion
  of the universe is expanding faster than it had
  in the past.
• 2. infer that dark energy is causing this

                              Today's universe
is expanding at an accelerating rate because
'dark energy' counteracts the force of gravity.
In the early universe matter was closer together,
and gravity still slowed its expansion.