The Beginnings of Cosmology
Earth and Space Science
Ancient People
• Sailors—used stars to navigate
• Farmers—used changes in seasons to plant
and harvest
Mythology
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Constellations
Same Clusters, different pictures
Celestial Sphere
Ancient Chinese
Greeks
Middle Ages
– Chinese and Muslims still learned/Europe did
not
Architecture
• Stonehenge
Temple and
ancient
calendar that
shows
positions of the
sun and the
moon at
different times
during the
year.
Architecture
• Chitzen Itza
People at Chichén Itzá can
see “the snake,” an apparition
made of shadows that
descends the stairs at El
Castillo during the solar
equinoxes each spring and
fall. At El Caracol, dubbed
“the observatory,” narrow
shaftlike windows frame
important astronomical
events. One such window
marks an appearance of Venus
at a particular point on the
horizon that takes place—like
clockwork—once every eight
years.
Architecture
• Sun Dagger in Chaco Canyon, NM
(calendar)
• At summer solstice, a vertical shaft
of light pierces the main spiral
exactly at its center. On the winter
solstice, two shafts of light perfectly
bracket the same spiral. Light shafts
strike the center of a smaller spiral
nearby on the spring and
fall equinoxes.
Architecture
• Big Horn Medicine
Wheel (28 Spokes)
If you stand or sit at one
cairn looking towards
another, you will be
pointed to certain places
on the distant horizon.
These points indicate
where the Sun rises or sets
on summer solstice and
where certain important
stars rise heliacally, that
is, first rise at dawn after
being behind the Sun. The
dawn stars helped foretell
when the Sun ceremonial
days would be coming.
The area is free of snow
only for 2 months -around the summer
solstice.
Geocentric View
• Until 16th century
• Aristotle—4th century B.C.
– Planets moved in circles around the earth
• Ptolemy—140 A.D.
– 80 circles; very complex
• Aristarchus of Samos—3rd century A.D.
– Proposed that planets orbit the sun
Heliocentric View
• Nicholas Copernicus—16th century
– Earth spins on its axis and orbits the sun; only the moon
orbits the earth
– Earth is round—studied lunar eclipses
• Galileo Galilei—16th century
– Popularized Copernicus’s book. It was banned in 1611
by the Catholic Church until the end of the 18th century.
He refused to stop teaching the heliocentric view and
was placed under house arrest in 1633 for the rest of his
life. (1642)
– Invented the modern telescope
Heliocentric View
• Johannes Kepler—1500s
– Developed the laws of planetary motion
– Worked for Tycho Brahe who compiled data
that led to Kepler’s conclusions.