Spherical Observation

Illustration of the Middle Ages' spherical world-view.

The idea of a celestial sphere which appears to surround the earth. This perception is an important step from simple observation of the stars to constructing astrology as a cosmic system. Since ancient times, Hellenistic astrologers determined mathematically that the earth was actually round, not flat; and conceptualized the heavens as one or a series of spheres surrounding the earth, each with its own planet.

The Ptolemaic World-view (order of spheres from Earth outward) is:

1. Moon
2. Mercury
3. Venus
4. Sun
5. Mars
6. Jupiter
7. Saturn
8. Fixed Stars
9. Primum Mobile (First Moved).

See also

• Celestial Sphere (Astronomy)
• Geocentric Model
• Harmony of Spheres

Ptolemy's sky.

Weblinks

• Wikipedia: Cosmos
• Wikipedia: Geocentric model