Impressive that Hipparchus of Rhodes and Copernicus noticed the precession of the equinoxes. That requires detailed record keeping. I wonder how Gilbert learned about Hipparchus.
Newton's law of gravity predicts the paths of planets, yet it does not explain why all planets move in the same plane and the same direction. That planets orbit the sun is unbelievably unlikely. An orbit only works for exact distances and weights. Looking forward to read about the role magnetism and electricity might play in that!
The entry for Hipparchus of Nicaea (where he was born) in the Biographical Encyclopedia of Astronomers has the following:
"He compiled the first trigonometric table (giving the chord function) and may well have invented trigonometry. Hipparchus introduced 360° angle measure and sexagesimal arithmetic from Babylon, invented a stellar magnitude scale that we still use (in updated form) today, and possibly invented the planar astrolabe."
Given the geographical position of Rhodes, close to the Hellenistic Seleucid Empire, whose capital was Babylon, Hipparchus would have had access to Babylonian astronomical records. Much of what we know about Hipparchus comes from Ptolemy or Pliny the Elder.
Impressive that Hipparchus of Rhodes and Copernicus noticed the precession of the equinoxes. That requires detailed record keeping. I wonder how Gilbert learned about Hipparchus.
Newton's law of gravity predicts the paths of planets, yet it does not explain why all planets move in the same plane and the same direction. That planets orbit the sun is unbelievably unlikely. An orbit only works for exact distances and weights. Looking forward to read about the role magnetism and electricity might play in that!
The entry for Hipparchus of Nicaea (where he was born) in the Biographical Encyclopedia of Astronomers has the following:
"He compiled the first trigonometric table (giving the chord function) and may well have invented trigonometry. Hipparchus introduced 360° angle measure and sexagesimal arithmetic from Babylon, invented a stellar magnitude scale that we still use (in updated form) today, and possibly invented the planar astrolabe."
Given the geographical position of Rhodes, close to the Hellenistic Seleucid Empire, whose capital was Babylon, Hipparchus would have had access to Babylonian astronomical records. Much of what we know about Hipparchus comes from Ptolemy or Pliny the Elder.