Who Am I

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Who Am I?
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What do I do?
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What do I do?
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What do I do?
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What do I do?
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What do I do?
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What do I do?
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What do I do?
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What do I do?

• ASTROPHYSICS That branch of astronomy which
  treats of the physical or chemical properties of
  the celestial bodies. Hence astrophysicist, a
  student of astronomical physics.
• ASTRONOMY The science which treats of the
  constitution, relative positions, and motions of
  the heavenly bodies that is, of all the bodies
  in the material universe outside of the earth, as
  well as of the earth itself in its relations to
  them.

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Our Universe
Today we will talk about

• What it is like, how it started, how it evolved
  to its current state, and how it will end

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• First, lets look at some of the objects we might
  find if we explored our Universe

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Where do we live?
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Where is the Earth?
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The Solar System
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Q What is a STAR?
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Our Sun is a star!
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Stellar Facts

• A star is a big ball of burning gas
• Our Sun is a very average star
• When we look out into the night sky, many of the
  stars we see are very similar to our own sun
• In fact some of these stars also have planets,
  just like our own Solar System

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What is this?
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What is it made of?
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MANY STARS
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MANY STARS
SOME SUN-LIKE
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Galactic Facts

• Stars tend to group together to form galaxies
• Galaxies contain hundreds of thousands of stars
• At the centre of most galaxies is a massive black
  hole!
• Our sun is part of a galaxy

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You are here!
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Our Galaxy from the Earth
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• We live on the Earth
• The Earth is a planet in the Solar System,
  orbiting our star which we call the Sun
• The Sun is part of a galaxy
• When we look out into the sky at night, all of
  the stars we see are in our galaxy
• But our galaxy is just one of many..

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Galaxies Hubble Space telescope image
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Zoom out - galaxies form filaments and voids
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• It is hard to comprehend the size of the
  Universe!
• We will now all help make a scale model of the
  solar system to get an idea of the distances we
  are talking about

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IN THE BEGINNING.
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EVERYTHING!
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EVERYTHING!
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STARTS EXPANDING..
EVERYTHING!
ENERGY INCREASING, BECOMING LIKE A BOMB.
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Tick tick tick
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BOOM!
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The Big Bang

• Not really an explosion
• Universe expanded rapidly as a whole
• (Universe is still expanding today as a result of
  the Big Bang)
• Matter was created in the form of tiny particles
  (protons, neutrons, electrons)
• Too hot for normal stuff to form (eg atoms,
  molecules)

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COSMIC SOUP
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COSMIC SOUP
PROTON
NEUTRON
ELECTRON
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300,000 Years Later..

• Universe much cooler, atoms start to form..
• Hydrogen, Helium, normal stuff

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Universe is now a GAS
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Universe is now a GAS
HELIUM
HYDROGEN
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GRAVITY!
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Gravitational Collapse

• We started with a uniform gas
• Small regions became more dense
• The denser regions had larger gravity and started
  to pull other particles towards them
• The gaseous Universe began to look clumpy

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Gravitational Collapse
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Gravitational Collapse

• Regions with more particles (higher density)
  become gas clouds
• Gas clouds become stars and galaxies
• Galaxies congregate together in filaments, groups
  and clusters

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If we could view the Universe from outside, if
would look like this
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But we are inside one of these galaxies, so all
we see are the nearby stars. We can see other
galaxies if we use a telescope
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The Gemini Telescope
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Future?

• The Universe is still expanding
• All galaxies are moving apart
• The explosion of the big bang is still
  happening!
• It may contine expanding forever
• Or is may stop expanding, and fall inwards in a
  big CRUNCH!

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What have we learnt?

• The Universe started with a BIG BANG
• Gradually the particles were drawn together under
  GRAVITY to form STARS and GALAXIES
• Many stars have planets around them
• The fate of the Universe is uncertain

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THE END