Transcript The REAL OCCULT - Montgomery College

Patterns in Celestial Motion
By Dr. Harold Williams
of Montgomery College Planetarium
http://montgomerycollege.edu/Departments/planet/
Time counting repeating patterns
in the sky
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A second, 1/60 of a minute, 1/(24*60*60)=1/86,400 of a day
A minute, 1/60 of a hour, 1/(24*60)=1/1440 of a day
A hour, 1/24 of a day
DAY, originally from sun rise to sun rise or sun down to sun down,
now a rotation of the earth about its axis
A week, Jewish bundling of days, sacred calendars
MONTH: originally a lunation (same moon to identical moon)
YEAR: originally a revolution of the sun around the earth through the
ecliptic, now a repeat of the earth around sun in its orbit.
A decade, century, millennium: different bundling of years
PRECESSION CYCLE: originally motion of the first day of a season
around the ecliptic, now cycle of the rotation axis (day and night axis)
about the year axis (this angle is around 23 ½ degrees now and takes
around 26,000 years)
GALACTIC YEAR: revolution of solar system about the Galactic
center in an orbit of around 250 million years.
Day and Night most basic, what you
see every day, without going into
outer space!
From outer space since ~300BCE
First of all earth is round
• It looks flat locally to me and you.
• Aristotle, shadow of the earth on the moon
during a lunar eclipse is always round.
• Greek sailors observed that when ships left
the harbor the top of the mast disappeared
last and the bottom of the ship first. So the
earth is definitely curved.
• But does the central fire, the sun, move
around the earth or the earth rotate.
History and Social Studies is very
important in Science (Aerospace)
• Evolution of models to explain things over time.
• You really can’t understand day and night motion
without folding in yearly motion particularly when
you start observing the changes in the night sky
through out the year. This started a long time ago.
• Language, reading and writing are essential.
• Mathematics, the self consistent abstraction of
reality is very useful.
Celestial Sphere
Celestial sphere on
Latitude Protractor
Celestial Sphere Rectified for
the North Pole
Celestial Sphere Rectified for
the Equator
Celestial Sphere Rectified for
the some place like here
The Celestial Sphere
• Zenith = Point on the
celestial sphere
directly overhead
• Nadir = Point on the
c.s. directly
underneath (not
visible!)
• Celestial equator =
projection of Earth’s
equator onto the c.s.
• North celestial pole =
projection of Earth’s
north pole onto the
c.s.
The Celestial Sphere (II)
90o - ℓ
ℓ
• From geographic
latitude ℓ (northern
hemisphere), you see
the celestial north pole
ℓ degrees above the
horizon;
• From geographic
latitude - ℓ (southern
hemisphere), you see
the celestial south pole
ℓ degrees above the
horizon.
• Celestial equator culminates 90o – ℓ above the horizon.
Night Time Star Motion
Round Earth Rotating now
Putting DAY and YEAR
together the modern way
The Annual Motion of the sun
Due to Earth’s revolution around the sun, the sun appears
to move through the zodiacal constellations.
The sun’s apparent path on the sky is called the ecliptic.
Equivalent: The ecliptic is the projection of Earth’s orbit
onto the celestial sphere.
The Seasons (IV)
Earth’s orbit (eccentricity
greatly exaggerated)
Earth in
January
Earth in July
sun
Earth’s distance from the sun has only a very minor
influence on seasonal temperature variations.
The Motion of the Planets (I)
The planets are orbiting the sun almost exactly in
the plane of the ecliptic.
Venus
Mercury
The moon is orbiting Earth in
almost the same plane (ecliptic).
Precession