Timeline of Orbital Mechanics
A chronological overview of major milestones in humanity's understanding of how celestial bodies move.
| Date | Event |
|---|---|
| ~350 BCE | Aristotle describes a geocentric cosmos with crystalline spheres. |
| ~150 CE | Ptolemy publishes the Almagest, refining the geocentric model with epicycles and deferents. |
| 1543 | Copernicus publishes De Revolutionibus, proposing a heliocentric model with circular orbits. |
| 1572 | Tycho Brahe observes a supernova, demonstrating that the heavens are not unchanging. |
| 1576–1597 | Brahe makes decades of precise observations from his observatory on Hven. |
| 1596 | Kepler publishes Mysterium Cosmographicum. |
| 1600 | Kepler joins Brahe in Prague. |
| 1609 | Kepler publishes Astronomia Nova containing his First and Second Laws. |
| 1619 | Kepler publishes Harmonices Mundi containing his Third Law. |
| 1687 | Newton publishes Principia, deriving Kepler's laws from universal gravitation. |
| 1846 | Neptune discovered based on gravitational perturbation calculations. |
| 1915 | Einstein's general relativity explains Mercury's orbital precession. |
| 1957 | Sputnik 1 launched—Kepler's laws applied to artificial satellites. |
| 1969 | Apollo 11 Moon landing uses orbital mechanics derived from Kepler and Newton. |
| 2009 | Kepler Space Telescope launched, using the Third Law to characterize exoplanets. |
See the Kepler biography for more on his personal story, or the Three Laws Overview for the science.