H'A'L' Astronomy School

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H.A.L. Astronomy School
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Size and Distance Matters

• Or, Matters of Size and Distance in the Solar
  System and the Universe

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The Scale of the Solar SystemTheres a lot of
SPACE in SPACE! Incredible Astronomy
Demonstration 1

• If the Earth was a peppercorn
• Then the Moon would be the size of a head of a
  pin 2.5 away from the Earth
• And the Earth/Moon combination would orbit a
  volleyball-sized Sun at a distance of 78 feet!

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The Scale of the GalaxyIncredible Astronomy
Demonstration 2
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The Scale of the Solar System

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The Scale of the Solar System

Sun

Nearest Star
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The Dimensions of the Solar System Compared to a
Single Light Year
An Analysis by Jerry Persall June 19, 2003
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Live Celestia Demonstration
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Sky Telescope, July 2003, p. 66
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Excel Worksheet Handout
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Conclusion

• The diameter of the solar system is nowhere close
  to being measurable in terms of light years, even
  a single light year!
• It is not 1/10th, 1/100th, or even 1/1,000th of a
  light year!
• The diameter of the solar system is, at best,
  around 16/10,000th of one light year (0.0016)!
• It is, however, on average, around 12/10,000th
  (0.0012) of a light year.

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Or is It? What is the Actual Extent of the
Solar System?And by Logical ExtensionWhat
Might Be the Actual Extentof Other Solar
Systems?Or, Where Do Solar Systems End?How Far
Away from the PrimaryStar(s) Do They Extend?
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100,000 AU 1.6 light-years
30,000,000,000,000 kilometers 18,000,000,000,000
miles 3 light-years
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Stellar Distances
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The Milky Way Galaxy Home A Very Typical Classic
Grand Spiral, One of Billions in the Universe
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Nearly Symmetrical Spiral Diameter(1) 125,000
light-years
125,000 light-years
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Nearly Symmetrical Spiral Diameter(2) 125,000
light-years
125,000 light-years
125,000 light-years
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Locating Earth in the Milky Way Galaxy
The Sun
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The Naked-Eye Limit of Visibility Within the
Overarching Vastness of the Milky Way Galaxy
The Sun
Circle of 2,000 LY radius
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• "Space," says Douglas Adams' The Hitchhiker's
  Guide to the Galaxy, "Is big.  Really big.  You
  just won't believe how vastly hugely
  mind-bogglingly big it is.  I mean, you might
  think it's a long walk down the road to the
  chemist, but that's just peanuts to space."

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The Distance to the Nearest Star

• The distance from the Sun to Proxima Centauri
  is 4.22 light years (or 260,000 AU.)