The Beginnings of Cosmology

1
The Beginnings of Cosmology

• Earth and Space Science

2
Ancient People

• Sailorsused stars to navigate
• Farmersused changes in seasons to plant and
  harvest

3
Mythology

• Constellations
• Same Clusters, different pictures
• Celestial Sphere
• Ancient Chinese
• Greeks
• Middle Ages
• Chinese and Muslims still learned/Europe did not

4
Architecture

• Stonehenge

Temple and ancient calendar that shows positions
of the sun and the moon at different times during
the year.
5
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 placelike
clockworkonce every eight years.
6
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.

7
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.
8
Geocentric View

• Until 16th century
• Aristotle4th century B.C.
• Planets moved in circles around the earth
• Ptolemy140 A.D.
• 80 circles very complex
• Aristarchus of Samos3rd century A.D.
• Proposed that planets orbit the sun

9
Heliocentric View

• Nicholas Copernicus16th century
• Earth spins on its axis and orbits the sun only
  the moon orbits the earth
• Earth is roundstudied lunar eclipses
• Galileo Galilei16th century
• Popularized Copernicuss 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

10
Heliocentric View

• Johannes Kepler1500s
• Developed the laws of planetary motion
• Worked for Tycho Brahe who compiled data that led
  to Keplers conclusions.