Astronomia Nova Pdf !full! -

If you are looking for the original 1609 text (titled Astronomia Nova ΑΙΤΙΟΛΟΓΗΤΟΣ seu physica coelestis ), several digital libraries offer high-resolution scans:

Unlike his predecessors, Kepler sought a physical cause (a "magnetic" force from the sun) for planetary motion, moving astronomy from pure math into the realm of physics. Conclusion astronomia nova pdf

Offers beautiful, high-resolution scans of the original 1609 edition. If you are looking for the original 1609