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Sketch in De Facie in Orbe Lunae

Johannes Kepler

A geometric diagram drawn by Kepler in his own translation of Plutarch's work on the Moon, linked to his lunar studies.

This is Kepler's own hand-drawn diagram from his translation of Plutarch, showing his lunar studies.

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Black-and-white scanned page showing a geometric diagram with labeled points (c, f, l, m, n, o, r, e, d, x, h, b, i, p, q, s, g) and lines forming a central vertical axis, a triangle at top, and arcs along the bottom, drawn in a historical printed book.
Johannes Kepler, sketch in his translation of Plutarch's De Facie in Orbe Lunae, p. 123.

About this source

What it is

This is a page from Kepler's translation of Plutarch's essay On the Face in the Moon, showing a geometric diagram he drew himself with labeled points and lines forming axes, a triangle and arcs.

The sketch is part of a printed book and survives as a scanned page.

Why it matters

Kepler used geometry to think through astronomical problems, including ideas about the Moon that later fed into his fictional work Somnium, an early story imagining travel to the Moon. The sketch shows the link between his mathematical work and his imaginative writing.

Look closer

  • What might the labeled points and lines represent about the Moon or Earth?
  • Why would an astronomer use geometry to explore ideas about space travel?
  • What does this sketch suggest about how Kepler worked through problems on paper?

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

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Title page of Astronomia Nova, printed in Latin with mixed roman and italic capitals and a Greek subtitle. It reads Astronomia Nova, Aitiologetos, seu Physica Coelestis, on the motions of the star of Mars, from the observations of Tycho Brahe, by Johannes Kepler, Prague, 1609. A small library stamp appears at the lower left.Book

Secondary source

Astronomia Nova

Johannes Kepler · 1609

Title page of Johannes Kepler's Harmonices Mundi, 1619, printed in Linz, Austria. It lists the five books in Latin, shows a small woodcut vignette of a winged figure, and bears handwritten notes in pencil at lower left.Book

Primary source

Harmonices Mundi

Johannes Kepler · 1619

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.Book

Secondary source

Mysterium Cosmographicum

Johannes Kepler · 1596 (2nd edition 1621)

Book

Secondary source

The Martyrs of Science: Galileo, Tycho Brahe and Kepler

David Brewster

Two-page scan of an early 17th-century book: on the left, an engraved frontispiece of a domed rotunda with columns, astronomical instruments and figures, and a tablet reading Tabulae Rudolphinae; on the right, a title page in Latin with large capitals announcing Tabulae Rudolphinae by Johannes Kepler, dated 1627, with a red library stamp at top right.Book

Secondary source

Rudolphine Tables

Johannes Kepler · 1627

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