Scientists and historians needed a full translation that captured Kepler’s “war on Mars”—his ten-year struggle to reconcile Tycho Brahe’s precise observations with a physical model of the solar system.

If you are looking for a legal, accessible version of this 600-page behemoth, try these avenues: Internet Archive (Archive.org):

The translation covers the entire work, including Kepler's introductory essays, detailed mathematical proofs, and his step-by-step narrative of the discovery process.

Cracking the Code of the Cosmos: Finding the English Translation of Kepler’s Astronomia Nova For nearly 400 years, Johannes Kepler’s masterpiece, Astronomia Nova

Published in , Astronomia Nova (New Astronomy) is one of the most important books in the history of science. It didn't just provide data; it changed the "how" of science.