1. The History of Astronomy
Part One
The Ancients
Astronomy “BC”

2. Eudoxus (400-347 BC) first known Geocentric (Earth-centered) model
It was (from Earth out): The Moon, Inferior Planets, Sun, Superior Planets & stars
all orbiting in circles…
On nested Spheres
It explained:
the phases of the Moon,
Eclipses,
why Inferior Planets are always near the Sun.

3. Aristotle ( BC)
The Ancient Greeks believed the Earth was a sphere.
As early as 500 BC Pythagoras suggested that the Earth was a sphere as it was the ‘perfect shape.’
Later Aristotle gave two reasons to believe the Earth was round:
The shape of Earth’s shadow on the moon during an Eclipse is always curved, only a sphere can do this.
Some stars are only visible from certain places on Earth

4. Aristotle’s Physics Everything is made of the 4 Elements
Which of these an object is made of determines….
where in the universe the object belongs
Fire at the highest level Air next level down
Water below the Air Earth lowest level
The natural state of an object at rest at its proper level.
Objects move in two ways
Naturally seeking to return to its proper level
Unaturally or Violently when it is forced to move.
Unless forced to move all objects come to rest at their proper level