Download Galileo and Newton

The Ordered Universe
The Birth of Modern Astronomy
(Trefil & Hazen, The Sciences, Ch 2)
Homer’s “Bear that never bathes”
Stonehenge
…one of several old
“time-reckoning”
machines. It’s
moving parts are in
the sky.
Ancient astronomy
Great Pyramid of Giza
…was aligned to the
pole star, and it was
possible to read the
seasons from the
position of the
pyramid’s shadow.
The Mayans of Yucatan
…inscribed stone
monuments with
formulae for
predicting solar
eclipses
Plains Indians
• Recorded the rising
points of the bright
stars, to record
seasonal grazing
patterns.
Political Power
…Columbus
influenced native
people to provide
food for his crew
by warning of “an
inflamed and angry
moon.”
Brief Overview of Early Science
• Greece, 4th C B.C.
• Roman Empire Fell,
5th C A.D.
• Chinese, Polynesians,
Arabs
• Islamic influences in
Spain 10-12th C
• Universities emerge in
Europe, 13th C
• Printing press, 15th C
• Copernican hypothesis
heliocentrism 15th C
• Galileo and “scientific
method” 17th C
The Ordered Universe
Part 1:
Ancient Astronomers
Ancient China
• Working calendar 13th
Century B.C.!
• Star Catalog with 800
entries, 350 B.C.!
• Observed comets and
supernovas
Babylonian Astronomy
• Oldest scientific
documents
• 800 B.C.
• Record eclipses,
positions of planets
and rise/setting of the
Moon
Greek Astronomy
600 B.C. to 200 A.D.
• Thales introduced geometrical ideas into astronomy.
• Pythagorus universe as a series of concentric spheres
• Eudoxus the idea of rotating spheres to account for the
observed complexities of planetary motions.
• Aristotle correct explanation of lunar eclipses; sound
argument for the spherical shape of the earth.
Astronomy at Alexandria
3rd Century B.C.
• Aristarchus
• Determined size and
distance of Sun and
Moon rel to Earth
• Developed 1st
heliocentric model
• Eratosthenes
• Made accurate
calculation of the size
of the Earth
Claudius Ptolemy
• Greek astronomer
from 2nd Century,
proposed first
enduring theory of
the universe, an
Earth-centered or
Geo-centric model.
Occam’s Razor
and interpreting oddities
• 14th Century English Philosopher
• Given a choice, the simplest solution to a
problem is most likely to be right.
Stonehenge
The Ordered Universe
Part 2:
Birth of Modern Astronomy
The “Fab. Four”
Copernicus, Brahe, Kepler, Galileo
(a)
(b)
Figure 2-5
The Ptolemaic (a) and Copernican (b) systems both
assumed that all orbits are circular. The fundamental
difference is that Copernicus placed the Sun at the center.
Mikolai Kopernik, 1473
• Copernicus
outlined a theory
for a sun-centered
or “heliocentric”
universe
• 1543,
On the Revolutions of
the Spheres
Tycho Brahe,1546-1601
Johannes Kepler, 1571-1630
Kepler’s Laws
• Planets orbit the sun in an ellipse.
• planets move more rapidly when close to
the sun and more slowly when distant from
the sun
• The cube of the mean distance of each
planet from the sun is proportional to the
square of the time it takes to complete one
orbit
Check your neighbor…
• Summarize key ideas of our attempt to make sense
of the universe
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Ancients of China, Egypt, Greece
Aristarchus
Eratosthenes
Ptolemy
Copernicus
Brahe
Kepler