Christoph Scheiner · 1630
Read the translation (PDF) · Editorial footnotes (PDF)
Rosa Ursina is the first comprehensive treatise on sunspots and a foundational work of telescopic solar astronomy. Scheiner marshals years of observations to demonstrate that the Sun rotates on its axis — with a period of about a month and the spots lying on or just above its surface — and establishes the inclination of the solar axis to the ecliptic.
The work runs to four books and combines three quite different kinds of writing. There are the observational records, with engraved plates of spot configurations tracked across the disc from day to day, which is the evidence the rotation argument rests on. There is a practical discussion of instruments and of safe solar-projection methods — how to observe the Sun without destroying one’s eyes, a problem Scheiner had every reason to take seriously. And there is a long polemic on the history and priority of the sunspot discovery.
The polemic dominates the opening. Book One begins with the occasion of writing at Rome and proceeds chapter by chapter against Galileo, argued around the pseudonym “Apelles” under which Scheiner had first published: that Apelles did not take his doctrine of the spots from his censor, that he did not claim to be the first discoverer after the censor, with the antitheses of censor and Apelles set out point against point. The reading layout is dense — two columns, heavy marginal and interlinear glossing, interleaved with full-page plates.
The rotation of the Sun and the tilt of its axis are established here, and established well: Scheiner’s spot observations are careful enough that later astronomers used them. The priority quarrel with Galileo, tedious as it reads, is part of the historical value — it preserves in detail how a scientific dispute was actually conducted in the 1620s, by whom, and on what grounds. The book remained the standard reference on solar phenomena for over a century.
The translated source is the 1630 printing, dedicated to Paolo Giordano II Orsini, Duke of Bracciano — whose family emblem, the rose and the bear, supplies the book its otherwise puzzling title.