Kepler's Mars observations

Timeline

1. 1596Tübingen · Baden-WürttembergKepler completed Mysterium Cosmographicum in Graz and published it in Tübingen, explaining the distances of the six planets from the Sun by nesting the five regular solids, with the calculation of Mars's orbit becoming the key test of his model.
2. 1596–1597Graz · GrazKepler found his model deviated from Mars's predicted position by about 8 arcminutes, realized precision beyond Copernicus's circular hypothesis was needed, and sought Mars data from Tycho Brahe and other astronomers, laying the groundwork for the later elliptical orbit law.