Summary, and 20-20 Hindsight
Let’s recap.
Category Archives: Astronomy
From Kepler to Ptolemy 5
Origins of the Ptolemaic System
We’ve worked backwards from Kepler to Ptolemy. What inspired Ptolemy and his predecessors (Apollonius and Hipparchus) to come up with this scheme in the first place?
From Kepler to Ptolemy 4
Speed Laws
In Ptolemy’s system, the point on the deferent moves uniformly as viewed from a point called the equant point, or sometimes just equant. The equant, the center of the deferent, and Earth all lie in a straight line, with the center midway between Earth and the equant.
From Kepler to Ptolemy 2
I’ll begin with Kepler’s first two laws, and work backwards to Ptolemy’s system. Seeing Keplerian astronomy recast this way will expose the bones of the Ptolemaic system.
Deferents and Epicycles
From Kepler to Ptolemy 1
Quite some time ago I started writing up notes, for my own amusement, on the history of astronomy. I’ve worked on it on-an-off over the years, but there always seems to be a bit more I should add. Eventually the pdf version will be ready for prime time. Meanwhile I’ve decided to convert what I have into a series of posts. Enjoy!
Selections from the History of Astronomy
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Armillary Sphere, Facade of Santa Maria Novella (Wikimedia Commons)
Another post from the History Book Club, this time based on three books:
- To Explain the World: The Discovery of Modern Science, by Steven Weinberg.
- The Sun in the Church: Cathedrals as Solar Observatories, by J.L. Heilbron.
- The Composition of Kepler’s Astronomia Nova, by James Voelkel.
Filed under Astronomy, History Book Club
