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Johann Kepler, Tychonis Brahei dani Hyperaspistes (Frankfurt, 1625)

The Shield-Bearer for Tycho Brahe

In his second and last contribution to the “Controversy over the Comets,” Kepler stepped in as a “shield-bearer” to defend Tycho from Galileo’s attacks. As a champion of novel mathematical methods in science, Galileo might have had an incentive to make common cause with Grassi and Kepler against those who disparaged mathematical methods, but that would have required a more congenial attitude toward Tycho and his followers than Galileo possessed. In addition to opposing Grassi’s use of parallax to determine cometary positions, Galileo also ignored Tycho’s argument from the absence of stellar parallax about the problematic sizes of stars in the Copernican system.

Galileo's World Exhibition Location

Source: History of Science Collections

Section: Controversy

Section Number: 3

Object Number: 35

Subject Area(s): Philosophy, Astronomy

Time Period: 17th Century

Region(s): Europe, Germany

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Phases of Venus: Riccioli, New Almagest

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Six Cosmological Systems: Phases of Venus

Kircher-Cosmological Systems-Venus

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Elisabeth Hevelius: Observational Astronomer

Elisabeth Hevelius Learning Leaflet

How does the Sextant symbolize the person who worked on the famed Hevelius star catalog and star atlas throughout its production, from observation to publication? 

Elisabeth Hevelius, wife of Johann Hevelius, was an astronomer in her own right. They worked together in the observatory of their Gdansk home to measure angular widths and distances with a great sextant, which required two observers at a time. The Sextant was among the new constellations they proposed in Uranographia (1690), the most detailed and influential celestial atlas of the 17th century. The Uranographia contains 54 beautiful double page engraved plates of 73 constellations, and 2 oversized folding plates of planispheres.