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De revolutionibus orbium coelestium

Nicolaus Copernicus · 1543

Copernicus's 1543 book proposing that the Earth orbits the Sun; its 1616 ban set the stage for Galileo's trial for defending it.

Galileo's defense of this book's heliocentric theory, after its 1616 ban, led directly to his trial by the Church.

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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.
Nicolaus Copernicus, De revolutionibus orbium coelestium, 1543. Printed by Johann Petreius, Nuremberg.

About this source

What it is

This is Nicolaus Copernicus's book De revolutionibus orbium coelestium, printed in 1543 in Nuremberg. It presented a heliocentric model of the universe, challenging the long-accepted Earth-centered system of Ptolemy.

Why it matters

Galileo did not write this book, but his defense of its heliocentric ideas, based on his telescopic observations, brought him into direct conflict with church authorities. When the Catholic Church's Index placed restrictions on the book in 1616, it created the legal grounds later used against Galileo in his trial. This connects Copernicus's theoretical work to Galileo's practical, observational proof and the price he paid for supporting it.

Look closer

  • Why might a book written decades earlier still cause trouble for someone like Galileo?
  • What does the dedication to the Pope in Copernicus's preface suggest about how he hoped the book would be received?
  • How does evidence from observation (Galileo's telescope) relate to a theory proposed earlier without it (Copernicus's book)?

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

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Title page of the 1610 Latin book Sidereus Nuncius by Galileo Galilei, printed in Venice by Thomas Baglionus. Black text in several type styles, with a central woodcut emblem of a seated figure in an oval frame flanked by cherubs. Handwritten shelfmark appears at the bottom.Book

Primary source

Sidereus Nuncius

Galileo Galilei · 1610

Engraved oval portrait print of a bearded older man with receding hair, wearing a white collar and a buttoned dark coat, in an oval frame. Inscribed 'Galileus Galileus Florentinus' at top, 'Eques Octavius Leonus' and 'Romanus pictor fecit' at bottom, and dated '16 24' with 'Superiorum licentia'. Printed on cream paper with a grayscale color scale at right.Painting

Primary source

Portrait of Galileo Galilei (1624 print)

1624

Oil portrait of an elderly bearded man with a white collar, wearing a black robe, seated at a table with books, a pair of dividers in his raised hand, and a celestial globe to the left, in a dark background. A brass plaque on the frame reads Galileo Galilei.Painting

Primary source

Oil Portrait of Galileo in His Study

Unknown Italian painter · 18th century (?)

Oval-framed line engraving of an older bearded man in a large white collar and dark doublet, with a Latin inscription above reading Galileus Galileus Florentinus, and an artist credit below. Handwritten Italian caption on mount beneath.Painting

Primary source

Galileo Galilei, line engraving by Ottavio Leoni

Ottavio Leoni · 1624

Title page of the 1632 Florentine edition of Galileo Galilei's Dialogo, printed in large serif capitals with a decorative woodcut emblem, imprint 'In Fiorenza, Per Gio: Batista Landini MDCXXXII', and several library stamps and handwritten shelf marks.Book

Primary source

Dialogue Concerning the Two Chief World Systems

Galileo Galilei · 1632

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