The Universe, the Big Bang, Stars, and Galaxies

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The Universe, the Big Bang, Stars, and Galaxies
The universe is a pretty big place, its bigger
than anything anyone has ever dreamed of before.
So if it just us, seems like an awful waste of
space, right?
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Universe
Last scene Men in Black (110)
The Hubble Ultra Deep Field, or HUDF, is an image
of a small region of space in the constellation
Fornax, composited from Hubble Space Telescope
data accumulated over a period from September 3,
2003 through January 16, 2004. It is the deepest
image of the universe ever taken in visible
light, looking back in time more than 13 billion
years. The HUDF contains an estimated 10,000
galaxies. The total field of view represents only
1 ten millionth of the total sky.
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• consists of all matter, empty space, and energy
  that exists
• objects are so far away, we are seeing what they
  looked like millions of years ago
• the visible universe is a region some 28 billion
  light years in diameter.
• it takes one year for light to travel 5 trillion
  miles (a light year)
• around 14-20 billion years old

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• is expanding faster and faster

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The Big Bang Theory
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• Origins
• began with a large explosion called the big bang
  theory
• only energy before this, no matter
• first hydrogen and helium were formed
• larger elements were formed later by stars

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• Evidence
• is expanding, therefore must have been smaller at
  one point
• evident by galaxies red shift
• most look red because they are moving away from
  us
• if they were moving towards us, they would look
  bluer (blue shift)

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• cosmic background radiation
• scientists found noise in our galaxy that was
  the cosmic microwave background radiation
  predicted by the Big Bang theory
• most elements in universe are H and He
• when stars reach the end of their life cycle,
  they distribute C, O, and Fe into the universe
• if the universe was older, there would be more C,
  O, and Fe

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Stars
Show Planet and Stars Scale video
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• Closest star to Sun is Proxima Centauri
• 4.2 light years away
• life cycle varies depending on the size
• all begin life inside a huge cloud of gas (mostly
  hydrogen) and dust called a nebula

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• then turns into a protostar
• H is converted to He

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• gravity squeezes the atoms of a star so tight
  that the electrons are stripped away and the bare
  nuclei of atoms almost touch each other

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• The Hertsprun-Russell (H-R) Diagram
• graphs the brightness and temperature of stars
• helps astronomers understand how stars change
  over time

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• for average, Sun-sized stars
• eventually runs out of H
• core contracts, gets hotter making elements up to
  Fe
• expands outwards making a red giant

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• hydrogen fusion stops
• no more energy exploding outward
• gravity pulls matter inwards
• VERY high density, bright, and is called a white
  dwarf
• outer layers often expand and drift away creating
  a planetary nebula

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• for larger stars
• elements up to iron are fused together
• eventually may turn into a supernova
• quickly collapses because run out of energy and
  gravity is now the strongest force
• core collapses and then rebounds outward with a
  shock wave that makes a bright explosion
  (supernova)
• at this point, the heavier elements are finally
  created
• if the leftover core is very, very dense, it may
  form a very small neutron star or a black hole
  with VERY powerful gravity

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Galaxies

• a collection of millions or billions of stars
• we are in a spiral galaxy called the Milky Way
  (Monte Python Galaxy song - 243)
• nearest to us is the Andromeda galaxy
• 2.2 million light years from earth

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• galaxies can also be elliptical and irregular
  shaped.

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The End