Transcript History

History
• Astronomy is perhaps the oldest science.
• Stargazing came before language, before fire.
• What is “our” place in the universe and how do we fit in?
Modern Event Calendars
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Astronomical Event Recorded
Observatories
• a) Big Horn Medicine Wheel (Montana)
• b) Mayan Caracol (Mexico)
Big Horn
• The Big Horn Medicine Wheel in the Big Horn Mountains
near Sheriden, Wyoming was interpreted in 1974 as an
indicator of summer solstice sunrise and sunset, with other
alignments for the rising of certain stars (Aldebaran, Rigel,
and Sirius).
• Built about 1050 AD. Has 28 spokes, and is about 90 ft in
diameter.
• About 50 similar circles exist. The oldest is in Canada (built
about 2500 BC - at the same time as the Egyptian
pyramids).
Caracol
• Located at Chichen Itza, Yucatan, Mexico, the
Caracol Tower was built about 1000 AD.
• It has some solstice and equinox alignments, and
also some star alignments. More interesting are the
apparent alignments with Venus (one of their
"gods").
• Mayan tablets also mention the rising of Venus. The
alignments make sense in light of the written
records.
Caracol
Big Horn
Stonehenge
• Stonehenge (England)
• Inset displays sunrise on the summer solstice as seen from
the center looking east toward the heel stone.
Stonehenge
• Consists of several concentric circles built in three periods, beginning
about 2800 BC.
• The largest stones weigh 50 tons, and were transported from many
miles away.
• Viewed from the center, the sun rises over the heel stone at the
summer solstice. (This was first noted in modern history in 1771.)
• Many other alignments are verified by astronomical planetarium
computer simulations.
Sun Dagger, Aztec Calendar Stone
Sun Dagger
• Discovered in 1977.
• Anasazi Indians of Chaco Canyon, New Mexico constructed a spiral
rock carving on Fajada Butte.
• At noon on the summer solstice, a dagger of sun penetrates the center
of the spiral.
• On the autumnal equinox, a sun dagger passes through the center of a
small spiral on the left, and another passes on the edge of the large
spiral. At the Winter Solstice, a big sun dagger passes on either side of
the large spiral.
• Also marks a 19-year lunar cycle. (The spiral has 19 rings.)
Mounds
• Cahokia Mounds in southern Illinois near East St. Louis has
a circle of postholes interpreted in 1970 as an astronomical
indicator of summer solstice sunrise, winter solstice sunrise,
and equinox sunrise.
• The mound-building Indians in the Mississippi Valley
region began about 3000 years ago, and there were several
cultures, and three successive groups of Indians there. There
is much conjecture about their circles, but little organized
study.
Ancient Astronomer (Astrologers)
Arab Astronomers
at work keeping
the nobles
informed and
entertained.
A mix of science and
pseudo-science.
Astronomers and Astrologers
• In the ancient world Astronomers paid their bills and funded
their scientific pursuits by
– predicting astronomical events for nobles
•
•
•
•
eclipses
tides
comets
planetary motions
– casting horoscopes
– entertaining
• Astrology, although totally bogus, was good economics!
Astronomy Versus Astrology
Astrology is an ancient superstition that hold that a person’s personality
and actions are influenced by the positions of the sun, moon, planets,
and stars at the moment of birth. In addition, astrologers claim that
the daily changes in the location of heavenly bodies can influence
events in our everyday lives. All of this is summarized in a
horoscope, which includes a diagram of the zodiac, showing the
precise positions of the heavenly bodies in their orbits.
Is there any physical reason we should expect astrology to work, except
that it might appeal to our needs? There seems to be no way for the
various heavenly bodies to interact on the body of a baby at birth,
except via gravity. The force of gravity exerted on the baby by the
doctor is many times larger than that of the sun and planets. Thus, it
would seem more important where the doctors and nurses stand in the
room rather than the orientation of the sun, moon, mars and the earth.
Astronomy Versus Astrology
Is there any evidence that astrology does work? Astrology has been
tested many times over, and no legitimate test has proven any
astrological influence on our lives. Extensive tests have searched in
vain for relationships between birth date and profession, blood type,
handedness, divorce rate, etc.
Yes it is based on science: Positions via Celestial Mechanics
It is NOT a science. It can not make accurate, verifiable predictions.
NO it doesn’t influence our lives: Use it like you would flipping a coin
or for entertainment along with the Sunday Funnies or fortune
cookies.
Astronomy Versus Astrology TOP 10
• 10. Astronomers never try to contact dead Astrologers.
Astronomy Versus Astrology TOP 10
• 10. Astronomers never try to contact dead Astrologers.
• 9. Politicians wives never asked an astronomer for advice.
Astronomy Versus Astrology TOP 10
• 10. Astronomers never try to contact dead Astrologers.
• 9. Politicians wives never asked an astronomer for advice.
• 8. The positions of the stars, planets, etc. dictate an
astronomer’s evening observing schedule, but they dictate
all aspects of an astrologer’s life.
Astronomy Versus Astrology TOP 10
• 10. Astronomers never try to contact dead Astrologers.
• 9. Politicians wives never asked an astronomer for advice.
• 8. The positions of the stars, planets, etc. dictate an
astronomer’s evening observing schedule, but they dictate
all aspects of an astrologer’s life.
• 7. Telescopes come in a staggering array of shapes and
sizes. All Ouija boards look the same.
Astronomy Versus Astrology TOP 10
• 10. Astronomers never try to contact dead Astrologers.
• 9. Politicians wives never asked an astronomer for advice.
• 8. The positions of the stars, planets, etc. dictate an
astronomer’s evening observing schedule, but they dictate
all aspects of an astrologer’s life.
• 7. Telescopes come in a staggering array of shapes and
sizes. All Ouija boards look the same.
• 6. Carl Sagan did not have a 900 number.
Astronomy Versus Astrology TOP 10
• 5. Your VISA limit is of very litter interest to an astronomer.
Astronomy Versus Astrology TOP 10
• 5. Your VISA limit is of very litter interest to an astronomer.
• 4. Astronomers occasionally make accurate predictions.
Astronomy Versus Astrology TOP 10
• 5. Your VISA limit is of very litter interest to an astronomer.
• 4. Astronomers occasionally make accurate predictions.
• 3. Alcohol makes complex astronomical concepts more
difficult to comprehend. It makes astrological concepts
easier.
Astronomy Versus Astrology TOP 10
• 5. Your VISA limit is of very litter interest to an astronomer.
• 4. Astronomers occasionally make accurate predictions.
• 3. Alcohol makes complex astronomical concepts more
difficult to comprehend. It makes astrological concepts
easier.
• 2. Transposing two astronomical objects’ coordinates makes
a huge difference. Transposing two peoples’ horoscopes
makes no difference at all.
Astronomy Versus Astrology TOP 10
• 5. Your VISA limit is of very litter interest to an astronomer.
• 4. Astronomers occasionally make accurate predictions.
• 3. Alcohol makes complex astronomical concepts more
difficult to comprehend. It makes astrological concepts
easier.
• 2. Transposing two astronomical objects’ coordinates makes
a huge difference. Transposing two peoples’ horoscopes
makes no difference at all.
• 1. Astronomers believe in the truth of relativity. Astrologers
believe in the relativity of truth
The Scientific Method
Iterative Logic and Creativity
“Right-brain”
thinking
“Left-brain”
thinking
Science Questions
• Science is only interested in questions that have an
experimentally verifiable end.
• There must be a Test for wrongness or rightness.
• If there is nothing experimentally verifiable, there is no
science.
• Not interested in speculations, only what can and can not
happen.
• Beware Pseudo-Science (Astrology)
• Extraordinary Claims Require Extraordinary Evidence!
Our Place In the Cosmos
Aristotle and Ptolemy
Geocentric Theory
(Earth Centered View)
Copernicus and Galileo
Heliocentric Theory
(Sun Centered View)
Aristotle’s Perfect Spheres
Ptolemy
Developed the first
accurate star atlas, complete
with brightness assignments.
Geocentric “Earth-centered”
Universe.
Taught the perfection of the
heavens, spheres, and
natural circles introduced
by Aristotle.
The Enigma of the Planets
The retrograde loop
of Mars.
Planos ~ wanderer
The retrograde loops
of other planets over
the course of a year.
Epicycles
Explaining planetary
motion in a
geocentric model
of the universe using
perfect circles
was not easy.
Geocentric Solar System
This allowed the
earth to be
stationary in space,
in the center of
the universe, and
would describe
some of the
motions of the
heavens.
Retrograde Motion
• Mars Retrograde Motion
• Epicycles (Geocentric View)
Real Retrograde Motion
• Mars Motion (Heliocentric Theory)
Eratosthenes
Lived in Alexandria Egypt at the height of its glory as the
center of intellectual learning and knowledge in the ancient
world.
He learned from a friend, of a water well in Syenne Egypt,
near Aswan to the south. On a certain day of the year, the
city celebrates summer. On that day at noon, the sun does
not cast any shadows and you can see sunlight reflected
from the bottom of most wells.
Eratosthenes knew that no such day existed in his town of
Alexandria.
Models and Experimental Verification
The earth is round? The earth moves? Ludicrous?!
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Models and Experimental Verification
How big is the earth. How fast is it going?
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Sailing, sailing, over the ocean blue...
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Sailing, sailing, over the ocean blue...
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Sailing, sailing, over the ocean blue...
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Sailing, sailing, over the ocean blue...
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Sailing, sailing, over the ocean blue...
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Sailing, sailing, over the ocean blue...
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Sailing, sailing, over the ocean blue...
Eratosthenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Sailing, sailing, over the ocean blue...
The earth is round?
Eratothenes Knew
The moon and sun are round.
During lunar eclipses, earth’s shadow on the moon is round.
Ships at sea appear mast first and disappear mast last.
Hire a Runner to Step out the Distance
Stadia (unit of measure ~ football field (Roman Coliseum))
Size of the Earth
3600 = Circumference of the Earth
70
Distance from Alexandria to Syenne
What is the distance from
Alexandria to Syenne?
Earth As A Sphere
Circumference of the earth = (360/7) 50,000
= 24,000 miles
For p ~ 3
and D = 2 x Radius
2 p R = 24,000
R = 24,000/6
R ~ 4,000 miles Radius of the Earth
Scientific Analysis
Eratosthenes had measured the size of the earth to within 10%
of the actual value. Quite a feat.
But, science is not only about answering a question (how big
is the earth?), but following up on the consequences of the
theory or model.
If the earth is a sphere with a radius of 4,000 miles, what are
the consequences?
Consequences
Perhaps we can not believe the earth is flat. It must be a
sphere. But, at least let us believe it sits motionless at the
center of the universe with the stars and planets revolving
around us.
OTHERWISE…
Distance = Speed x Time
Distance = Circumference
Speed = v
Time = period of rotation
Consequences
Perhaps we can not believe the earth is flat. It must be a
sphere. But, at least let us believe it sits motionless at the
center of the universe with the stars and planets revolving
around us.
OTHERWISE…
Distance = Speed x Time
D = 24,000
t = 24 hours
Distance = Circumference
Speed = v
Time = period of rotation
Calculating Rotation Speed
D=vt
2Rp=vt
2 (4,000 miles) 3 = v (24 hours)
Do You Feel FAST!
D=vt
2Rp=vt
2 (4,000 miles) 3 = v (24 hours)
24,000 miles = v 24 hours
24,000 miles = v
24 hours
v = 1,000 miles/hour
Predictions
Spherical, Rotating Earth: Someone at the equator must move
at 1,000 miles/hour.
Experimental Verifications of the Rotating Earth:
– Focault Pendulum
– Coriolis Effect
– Planetary Motions
Galileo’s Observations
DEFENDER OF COPERNICAN HELIOCENTRIC THEORY
I. Craters on the Moon (imperfection)
II. Sunspots on the Sun (imperfection and solar rotation)
III. The Moons of Jupiter (earth is not the center of all things)
IV. The phases of Venus
I-III Represent Circumstantial evidence
IV DNA/fingerprints, undeniable proof
Galileo’s Phases of Venus
Heliocentric
Geocentric
Galileo’s Phases of Venus
Geocentric
versus
Heliocentric
Galileo and the Inquisition
Heliocentric Retrograde Motion of Mars
Planetary Scale Model
•
Planet
Solar
System
Scale
Model
Solar Distance (AU)
Relative Size (Earth =1.0)
Inches
Object
SUN
0.0
100
McEver Hall
Mercury
0.4
0.4
4
Baseball
Venus
0.7
1.0
10
Basketball
Earth
1.0
1.0
10
Basketball
Moon
1.0
0.3
3
Racquetball
Mars
1.5
0.5
5
Softball
Jupiter
5
11
110
Golf Cart
Saturn
10
9
90
Uranus
20
4
40
Neptune
30
4
40
Pluto
40
0.2
2
Bean Bag
Golf ball
Shapley’s Globular Cluster Distances
Ordinary
Each successive discovery removes us from a special place in
the universe.
More and more observations indicate that we (and earth)
are ordinary, even insignificant when compared to the vastness
of space.
We are a minor planet, around an average star, in an average
galaxy.
A Stellar Zoo
Solar Neighborhood
The Sun
(an average star)
and the stars
within 4 parsecs.
The Milky Way
You Are Here
One Galaxy Among Many
A Slice of the Universe
Each dot
represents
one galaxy.
Universe Scale
•
Scales and Sizes
• MOVIE: Powers of 10
Summary