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Secondary sourceBook1596 (2nd edition 1621)

Mysterium Cosmographicum

Johannes Kepler · 1596 (2nd edition 1621)

Johannes Kepler's 1596 book, the first full published defence of Copernicus's heliocentric theory, which tried to explain planetary spacing using geometry.

The earliest full published defence of Copernicus's heliocentric theory, extending it with geometric reasoning.

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Title page of Kepler's Mysterium Cosmographicum in Latin, printed in Frankfurt by Erasmus Kempfer for Godefridus Tampachius, dated 1621 (MDCXXI) on this edition. Aged, brownish paper with a red library stamp at right.
Johannes Kepler, Mysterium Cosmographicum, Frankfurt, 1621 edition (first published Tübingen, 1596).

About this source

What it is

Published in 1596 by the German astronomer Johannes Kepler, this book proposes that the distances between the six known planets could be explained using the five Platonic solids nested within spheres. A second, expanded edition appeared in 1621.

Why it matters

This was essentially the first attempt since Nicolaus Copernicus to argue that heliocentrism was physically, not just mathematically, true. Kepler saw his geometric model as revealing God's plan for the universe, showing how religious and scientific thinking were deeply intertwined for early defenders of Copernicus's system. The book helped establish Kepler's reputation and launched his lifelong work refining planetary astronomy.

Look closer

  • Why might Kepler have connected his astronomical theory to religious ideas about the Trinity?
  • What does it mean that Kepler had to remove a chapter on Bible interpretation before the university would let him publish?
  • How does Kepler's geometric explanation differ from how we understand planetary orbits today?

This book is part of the curated material that grounds the AI version of Nicolaus Copernicus, Johannes Kepler and Tycho Brahe on Humy.ai — when students ask about related events, the AI can quote it and cite it.

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Title page of Nicolaus Copernicus's De revolutionibus orbium coelestium, printed 1543 in Nuremberg by Johann Petreius. Large capitals read NICOLAI COPERNICI TORINENSIS, followed by the book title and an address to the reader in Latin. Handwritten ink marks read Bibliotheca and Univers, and a Greek motto appears below the text.Book

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De revolutionibus orbium coelestium

Nicolaus Copernicus · 1543

Engraved portrait print of Nicolaus Copernicus in an octagonal frame with stippled background. A man with wavy shoulder-length hair wears a fur-trimmed garment and holds a small armillary-style sphere. Caption reads NICOLAUS COPERNICUS, with publisher line Zwickau, bei Gebr. Schumann below.Painting

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Portrait of Nicolaus Copernicus (Schumann print)

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Scanned page from a 1543 printed book titled Nicolai Copernici, showing a diagram of concentric circles with the Sun at the center, labeled planetary orbits including Mercury, Venus, Earth (terra) with the Moon, Mars, Jupiter, Saturn, and the outer sphere of fixed stars. Latin text surrounds the diagram.Artifact

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Copernicus's Diagram of the Planetary System

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Engraved oval portrait of Nicolaus Copernicus, a man with wavy shoulder-length hair and a fur-collared garment, inside a decorative border with Latin inscriptions and dates, on a book page photographed on a dark background with a gray scale.Painting

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Engraved Portrait of Nicolaus Copernicus (Herzog August Library)

Unbekannt

Engraved portrait of Nicolaus Copernicus in an oval frame, shown on a book page with a page number 52 in the corner. The man has curly hair and wears a fur-trimmed garment. Latin inscription 'NICOLAUS COPERNICUS' appears at the bottom, with a verse text block below and a catalogue number beneath the page.Painting

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Portrait of Nicolaus Copernicus (Albertina Museum)

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