The "father of astronomy," he successfully predicted a solar eclipse that brought an end to a war between the Lydians and the Medes:
Thales
He taught that earth was a planet that rotated on its axis and revolved about the sun:
Aristarchus
This imaginary globe has stars attached to its surface:
celestial sphere
He thought circles and spheres were perfect and promoted the five regular solids; he also said the universe contained nested crystal spheres which held the planets, and spoke of "the music of the spheres."
Pythagoras
When an object appears to change position against the background of more distant objects due to a change in the location of an observer, we call this phenomenon---
Parallax
This Greek word means, "wanderer."
Planetes
When a planet seems to move backward (east-west) against the background of stars, its motion is
Retrograde
This Alexandrian librarian correctly measured the Earth's circumference:
Eratosthenes
