A tour of the Night Sky: Astronomy Made Simple

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A tour of the Night Sky Astronomy Made Simple

• Dr. Nathan Miller
• UWEC Department of Physics Astronomy

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Goals of class1. Learn how stars, sun, moon
and planets move through the sky2. Understand
how Copernicus and Co. (1473-1543) used that
alone to figure out the way the solar system is
put together
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Things you would study in a medieval university

• The Trivium
• Grammar
• Rhetoric
• Logic
• The Quadrivium
• Arithmetic
• Geometry
• Music
• Astronomy (Note Not a trivial subject!)

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Hogwarts classes

• Herbology
• Potions
• Charms
• Muggle Studies
• Care of Magical Creatures
• Defense Against the Dark Arts
• Astronomy

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Points of Light in the Sky
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A picture of 6 planets
Jupiter
Mars
Saturn
Venus
Mercury
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Two large sources of light
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Moon, Venus, Spica
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Practical Astronomy The Motions of the Stars
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Understanding the Motion of the Stars using the
Celestial Sphere
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Note The celestial sphere is not at some
specific location. It is just an imaginary
sphere used to discuss the locations of and
angles between the stars.
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Atlas holding a celestial globe (Roman copy of
200 BC Greek original)
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You go out and look at a star just above the
eastern horizon. Compared to the position of a
tree in the distance, an hour later, the star

• Is right where it was before
• Is directly above where it was before
• Is above and to the left of where it was
• Is above and to the right of where it was
• Is below where it was
• Is below the horizon

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How long was this camera exposure? A. 3 hrs
B. 8 hrs C. 12 hrs D. 20 hrs
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Could you (from Eau Claire) make a photo showing
complete circles? A. Yes B. No C. No
way to tell
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Exercise 1 Planisphere Star Motions
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Celestial Navigation
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From ancient times
To recent times
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To orient yourself and fix your location,
want1. Cardinal directions2. Latitude3.
Longitude
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• ?YOU ARE HERE

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Celestial Navigation Determine your location on
earth by measuring the elevations of stars above
the horizonThis works because at the same
moment in time, every location on earth sees a
unique view of the sky.
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Instruments Mariners AstrolabeSextant
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Step 1 Use Polaris to locate due north
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Step 2 Measure angle of Polaris above your
horizonHeight of Polaris above the horizon
your lattitude
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AT THE EQUATORYou go out and look at a star
just above the eastern horizon. Compared to the
position of a tree in the distance, an hour
later, the star

• Is right where it was before
• Is directly above where it was before
• Is above and to the left of where it was
• Is above and to the right of where it was
• Is below where it was
• Is below the horizon

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Person Standing at North Pole
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Zodiacal Constellations 12 constellations on
dotted line on the planisphere. They tell you
which direction you are looking out into space
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Exercise 2 Stars Around the WorldExercise 3
Celestial Navigation