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Tuesday, November 15, 2011

Early Astronomy and Astrology at HSS 2011

Posted by Darin Hayton on 11/15 at 10:52 PM

There were three panels at HSS this year devoted to early modern astronomy and astrology. Unfortunately, the first, “The ‘State’ of Science and Religion: Ingenuity and Institution in the Age of Galileo and Kepler,” occurred at the same time as the Antikythera panel. “Early Astronomy and Astrology” was the second. The third was the symposium on Robert Westman’s The Copernican Question. Rather good coverage of early astronomy.

This panel opened with two rather detailed and at times technical papers. Henry Zepeda started things off with “‘A Difficult Figure’: Ptolemy’s Menelaus Theorem in the Middle Ages.”

Henry Zepeda explaining the details of the Menelaus Theorem (Source: Author’s photo)

Zepeda recounted Ptolemy’s discussion of the Menelaus Theorem, pointing out that it was useful for converting between right ascension and declination and that it was useful for finding the rising times of constellations and planets. But its difficulty generated a rich commentary tradition in the middle ages and, importantly, Jabir ibn Aflah’s simplified alternative, found is his commentary on the Almagest. Nonetheless, Zepeda claimed, Latin astronomers continued to study Ptolemy’s more difficult proof.

Yaakov Zik then walked through “Kepler’s Novel Method of Calculating the Eccentricity of the Sun.”

Zik reading part of his paper on Kepler (Source: Athor’s photo)

According to Zik, Kepler rejected the traditional method of calculating the Sun’s eccentricity that relied on measurements of the seasons. Instead, motivated by his effort to confirm his polyhedral model for ordering nesting the planets, Kepler sought more precise data. [At this point I had to step out so I missed the remainder of Zik’s paper.]

Following these detailed and technical papers, Rachel Gostenhofer’s “Mathematical Astrology and other Failed Essays of the Scientific Revolution” was certainly lighter fare. She suggested that John Dee was, in fact, an important step toward science not as Renaissance magus in the manner that Frances Yates considered him important, but because he tried and failed to quantify astrological influence. Gostenhofer ladled out various medieval, early modern, and 19th-century efforts “to quantify” seemingly unquantifiable amounts—the amount of God’s grace or the amount of happiness. For her argument, she turned to Dee’s Propaedeumata Aphoristica in which he attempts to apply optics to astrology in order to quantify astral influences. He failed. But Gostenhofer claimed that in failing he helped to show which amounts could be quantified. In other words, Dee remains a key forerunner of the Scientific Revolution not in a positive sense but in a negative one, by showing through his failure where quantification could be successful and where it would fail.

Finally, in his “Past Portents Predict: Comets, Astronomy, and Historical Astrology” Adam Mosley analyzed catalogs of comets emerged in the 16th century as a distinct genre. By recounting previous appearances of comets and listing the effects that followed, these catalogs provided the empirical evidence for the common view that comets were portents—either signs or causes—of dire events: deaths of kings and princes, famines, wars, and plagues.

Adam Mosley draws attention to catalogs of comets (Source: Author’s photo)

Mosley suggested that historians of astronomy have neglected these catalogs because they have too readily categorized comets as astronomical phenomena and have focus on explaining how 16th-century astronomers came to see them as astronomical. Instead, he wants to draw our attention back to the meteorological texts, where comets regularly appear. He also argued that by looking at these catalogs we can begin to see that astronomers were invoking a particular form of knowledge, Historia, in much the same way physicians were. That is to say, history provided empirical data that grounded current interpretations and future predictions.

Tags: adam mosley, astrology, astronomy, claudius ptolemy, henry zepeda, hss 2011, johannes kepler, john dee, rachel gostenhofer, yaakov zik

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