Some History

This timeline illustrates the changing rates of progress in our understanding of gravity and planetary motion.

(Click on the timeline to expand it.)

The annotations are roughly separated into "experimental" (above the line) and "theoretical" (below it). Newton is exceptional for appearing on both sides. The long "dry spell" between Ptolemy and Copernicus is noteworthy: Aristotle's emphasis on the circle as a "perfect" geometric figure seems to have blinded thinkers for a sizable part of recorded history.

(View Cosmos DVD 2, episode 3, Kepler's life.)
Some particularly interesting dates:

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These dates represent first successes; for a more complete picture of the history of space exploration, see NASA's Chronology of Lunar and Planetary Exploration.

©2010, Kenneth R. Koehler. All Rights Reserved. This document may be freely reproduced provided that this copyright notice is included.

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