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Johannes Kepler

11 stories mention Johannes Kepler on DeadlyCurious.

The Cabinet June 27, 2026 · Hven, Øresund

The Danish Astronomer Who Was Given an Entire Island by the King of Denmark in 1576 to Build the Largest Pre-Telescopic Observatory in History

King Frederick II of Denmark granted Tycho Brahe the island of Hven in the Øresund Strait in February 1576 with funding to build a state-supported astronomical observatory. The resulting Uraniborg and Stjerneborg observatories operated from 1576 to 1597 and produced the most accurate pre-telescopic positional astronomy in history. The data set was the foundation on which Kepler's three laws of planetary motion were derived.

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The Cabinet June 24, 2026 · Alexandria

The Astronomy Book That Synthesised Three Centuries of Greek Observation and Ruled Europe for Fourteen Centuries

Claudius Ptolemy's *Mathēmatikē Syntaxis* — known to Europe as the *Almagest* through its 9th-century Arabic translation — was the single dominant astronomical reference work of the Western world from approximately 150 AD to 1543. Most of its observational content was inherited from Hipparchus of Rhodes three centuries earlier.

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The Footnote June 24, 2026 · Uraniborg, Hven Island

The Two-Metre Brass Arc That Made Tycho's Pre-Telescopic Astronomy Possible

The mural quadrant at Tycho Brahe's Uraniborg observatory was a brass arc mounted on a north-south wall and used for measuring the meridian altitudes of stars and planets. It was the largest and most accurate astronomical instrument of the pre-telescopic period and produced most of the data that Kepler would later use to derive the laws of planetary motion.

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The Footnote June 23, 2026 · Herrevad Abbey, Skåne (then Denmark, now Sweden)

The New Star Tycho Brahe Saw From Denmark in 1572

On the evening of 11 November 1572 a bright new star appeared in the constellation Cassiopeia. It was visible for sixteen months. Tycho Brahe — twenty-five at the time — measured it carefully enough to prove it sat above the Moon. The Aristotelian heavens that were supposed to be unchanging had quietly changed.

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The Cabinet June 23, 2026 · Duchy of Württemberg, Holy Roman Empire (modern southwestern Germany)

The Hundred-Year Witch Hunt That Killed Kepler's Mother and Almost Killed Württemberg

Between approximately 1560 and 1660 the Duchy of Württemberg in southwestern Germany executed approximately 350 accused witches. The peak years coincided with the Thirty Years' War. Johannes Kepler's mother Katharina was tried during the worst of it; she was acquitted; she died six months later anyway.

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