The Journey Begins

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The Journey Begins!

• For as long as there have been humans on earth,
  we have gazed into the night sky and wondered
• How far away is the moon?
• What are planets and comets?
• What are the stars, and why do they shine?

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Look Up! Wonder! Watch!

• The splendor of the star-filled night sky is one
  of the truly remarkable experiences of life.
• (Look up! Please.).

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First Quiz Whats Going On?

• Are there more stars in the visible universe than
  grains of sand on all the beaches of earth?

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First Quiz Whats Going On?

• Are there more stars in the visible universe than
  grains of sand on all the beaches of earth?

• Heavy elements in your body formed long ago deep
  inside stars?

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First Quiz Whats Going On?

• Are there more stars in the visible universe than
  grains of sand on all the beaches of earth?

• Heavy elements in your body formed long ago deep
  inside stars?

• Is the universe infinite in size? Finite? Edge?

• Is the universe changing? Expanding? Contracting?
  Forever?

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Astronomy Study the Physical Universe

• What does the universe contain?
• How is the universe organized?
• What does the universe look like?
• How is the universe changing? Past? Future?

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Goals Aspirations

• You should acquire perspectives on where you are
  in space and time.

• A realization that the universe is a rational
  place, it is not a hodgepodge of unrelated things
  behaving in unpredictable ways.

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Warning! Red Alert!

• You are not in the Star Trek universe!! (Old
  series or new.) Nor the Farscape, BattleStar
  Galactica, or SG-1 ones either.

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Distances "Our Place in Space."

• Universe
• V-a-s-t!!!!
• Gigantic
• HUMONGOID!!!
• Golly WHOMPERS big!!

Titan
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How to Cope?
Start thinking about every day experience!
Driving (travel time)
Flying (travel time)

• Washington D.C.
• Oklahoma City
• San Francisco

Oklahoma City London China
(1.5 hours)
(3 hours)
(19 hours)
(9 hours)
(38 hours)
(25 hours)
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Our First Step!

• Ah ha! We can now get a good "sense" for the size
  of the Earth!
• We have scaled up to a "mental model" for
  Earth-sized!

• (The Earth is still pretty large to me.)

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Compared to What?

• T-I-N-Y!!!!

Puny, Itty-Bitty
GoLlY WiLlIkErS SmAlLCompared to other nearby
objects and to the rest of the universe.
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Numbers

• Earth's Radius 6400 km 6.4 103 km (4224
  miles)

Sun's Radius 696,000 km 6.96 105 km. How
much bigger is the Sun than the Earth? (1,000,000
Earth's to make 1 Sun! - Volume)
Earth-Sun Distance 150,000,000 km 1.5 108
km 8 light minutes!!
Speed of Light 300,000 km/sec 3.0 105
km/sec (186,000 mi/sec)
One Light Year 6,000,000,000,000 6 trillion
miles traveled in one year.
Nearest Star? (Proxima Centauri) 4.0 1013 km
(4.2 light-years)
Center of Galaxy? (Milky Way)
189,000,000,000,000,000 km 20,000 light-years
2.0 104 lt.yr.
Nearest Galaxy? 23,700,000,000,000,000,000 km
2.4 106 light-years.
Radius of Observable Universe? (Approximation -
The limits to which we can see?) 12-15 109
light-years!
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Let's fit this into the brain.

• If Earth was pea-sized,.

• Sun is about a beach-ball in size.

(Next to Holloway Hall)

• Star? Anyone? Anyone? How far?

"NEW ZEALAND!"

• Only way to cope You have to make mental maps,
  models, ideas of your surroundings, then,,, just
  keep going! Home, town, state, country, globe,
  solar system, galactic area, milky-way,
  universe, etc..

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Keep Going!
Solar System - Light-minutes across.
Nearby Stars - Light years away.
Nearby Galaxies - millions of light-years
Our Galaxy? 10,000s of light years.

• Universe - billions of light years!

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Cosmic Time "Our Place in Time."
Earth around the Sun 1 year
Human Life 75 years (trips)
Sun around Galaxy 2.5 108 years
Age of Solar System 4.6 109 years (18
trips)
Age of Universe? 12-15 109 years
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What are we really seeing?
Keep in mind that we only observe the past!!

• We see the Sun as it was 8 minutes ago!
• "Galaxies" as millions of years ago.
• The farther into space we look, we see the
  universe as it was long ago.
• If we look as far as we can see! We are LOOKING
  TO THE BEGINNING OF TIME!!

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Adventure is Afoot!

• I hope this little introduction has gotten you
  excited about the adventure that astronomy can
  be.
• We are beginning a grand-tour of the universe
  from the small to large from the beginning of
  time to the end of time.
• I expect to encounter many surprises along the
  way.
• Get READY!!

We live in a wonderful world that is full of
beauty, charm, and adventure. There is no end to
the adventures that we can have if only we seek
them with our eyes open. Jawaharlal Nehru
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