Transcript History - The University of Oklahoma Department of Physics and

A Western History of Astronomy
Larry A. Maddox
Greeks were among first active stargazers.
Noted the changing sky.
Our name “planet” comes from the greek
word for “wanderer”
Observers were puzzled by the phenomenon
of retrograde motion exhibited by the
planets.
Retrograde motion of Saturn and Jupiter
Plato
Plato's Four Points
1. There is certainty.
2. Mathematics gives us the power of perception.
3. Though the physical applications of mathematics may
change, the
thoughts themselves are eternal and
are in another realm of existence.
4. Mathematics is thought and, therefore, it is eternal and
can be known
by anyone.
Pythagoras
The Pythagorean Paradigm
1. The planets, Sun, Moon and stars move in perfectly
circular orbits;
2. The speed of the planets, Sun, Moon and stars in
their circular orbits
is perfectly uniform;
3. The Earth is at the exact center of the motion of the
celestial bodies.
Eudoxus (sorry, no picture)
Aristotle
Aristotle
Adopted cosmology of Eudoxus.
Noted that southern stars get higher in the sky as
one goes south.
Noted that Earth cast a circular shadow during
a lunar eclipse.
From these observations, argued that Earth is
spherical
Aristarchus
Aristarchus
Broke with Greek religious tradition of
geocentrism
“The fixed stars and the Sun remain
unmoved”
“The Earth revolves about the Sun on
the
circumference of a
circle” (quotes are from
Archimedes, “The Sand Reckoner”)
Model is inferred from geometric
arguments
Hipparchus
Believed in pure observation.
Examine precise positions of stars.
Found the precession of the pole and the equ
Gave us the modern magnitude system.
Brightest stars are 1st magnitude.
Faintest stars are 6th magnitude.
Later found to be very (mathematically) regular i
divisions.
Claudius Ptolemy
Motion on the Epicycle
And then, not much happened
for a while...
Nicholas Copernicus
Tycho Brahe
Tycho's Inner Universe
Tycho
1572 noticed a “stella nova” in Cassiopeia.
November 11, 1572
Remained in the sky for a few months.
Published observations in Der Stella Nova
On the night of discovery, required several verificati
Johannes Kepler
Kepler
1604: observed another stella nova.
Named star and dedicated next book
for Tycho.
Kepler's Laws of Plantary Motion
1. The orbit of every planet is an ellipse, having the sun
at one of its foci.
Kepler's Laws of Plantary Motion
2. If a line, called a radius vector, is supposed to be dr
from the sun to any planet, the areas described by t
as the planet revolves in it orbit, are proportional to
times.
Kepler's Laws of Plantary Motion
3. The squares of the times of revolution of any two plane
are proportional to the cubes of their mean distances f
the sun.
Galileo
Observations of the Moon
And Venus
Galileo believed that Saturn was a “tri-form” planet.
Christian Huygens
Theorized that Saturn was surrounded by
a ring of material that was separated from
the sphere of the planet.
18th Century, William Herschel discovered Uranus, a new planet
beyond Jupiter. Barely visible with the unaided eye, Herschel made
the observation with his telescope.
Early in the 19th Century Adams (English) & LeVerrier (French)
independently calculated that there must be another planet beyond
Uranus that was producing small gravitational disturbances in Uranus'
orbit. First observed in 1846 by Hohan Galle, it was named Neptune.
(It was actually spotted earlier by Challis in Cambridge, but Challis did
not note his discovery until Galle reported his observation.)
1930 Clyde Tombaugh discovered Pluto.
1910 Harlow Shapley estimated the size of the Milky Way.
W. H.Pickering and Annie J. Cannon calculated the surface
temperatures of the stars.
Einstein (1905) developed the Theory of Special Relativity, based
1929 Hubble & Milton Humason discovered that the Universe
is expanding.
1938 Hans Bethe determined that the Sun's energy comes
from thermonuclear fusion reactions.
1940s Karl Jansky (from Norman, OK) observed that the
nucleus of the Milky Way and other celestial objects are strong
sources of Radio Waves in 1931. Based on radar technology
developed in WWII, Radio Astronomy becomes an active field
in the late 1940s.
1948 Geroge Gamov developed the Hot Big Bang Theory of
the origin of the Universe.
1950's chemical composition of the stars; stars build the heavy
elements via nuclear fusion reactions, mapped out in a famous
paper by Burbidge, Burbidge, Fowler & Hoyle.
1954 Radio Galaxies
1960-63 Quasars
1960s X-Ray &Infrared astronomy
1965 Arno Penzias and Robert Wilson from
Bell Laboratories discovered the cosmic
microwave background radiation remnant of
the Big Bang.
1968 Jocelyn Bell (Burnell) & Anthony
Hewish discovered Pulsars