Astronomia nova

ΑΙΤΙΟΛΟΓΗΤΟΣ seu physica coelestis, tradita commentariis de motibus stellae Martis ('New Astronomy')

In chapter 1 Kepler says the paths of the three outer planets, seen from a fixed Earth, are 'more truly in the shape of a Lenten loaf' than a ball of yarn, and draws the motion of Mars from 1580 to 1596 as a chain of loops (pp. 47–48 of the 1609 edition), as evidence against the Ptolemaic and Tychonic arrangements. The book then derives Mars's orbit from Tycho's observations, opposition positions included, and reaches the ellipse in chapter 59.