Johannes Honter’s celestial hemispheres
Johannes Honter (1498–1549), a cartographer and theologian from Transylvania (the modern Romania), published a pair of celestial hemispheres in 1532 with what was then a novel feature: they showed the constellations the right way round, as they appear in the sky. This might seem obvious to us now, but at that time astronomers were more familiar with globes than printed charts.
Dürer, Apianus, and their imitators had produced charts that depicted the constellations as they appear on the surface of a celestial globe, but the drawback was that the figures were mirror images of the way we see them from Earth. After Honter, the advantage of drawing the constellations the right way round became self-evident, although there were a few hold-outs such as Johannes Hevelius who still showed the constellations in globe view on his star atlas, Firmamentum Sobiescianum, a century and half later.
Another distinctive feature of Honter’s charts is that several of the constellation figures are clothed in contemporary European dress, unlike the classical nudes of Dürer and his followers – see, for example, Ophiuchus and Boötes. Honter’s charts first appeared in 1532 but were later reprinted a number of times, most notably in an edition of Ptolemy’s collected works, Omnia quae extant opera, published in 1541, and editions of Aratus’s Phaenomena in 1559 and 1576. Hence they were probably more widely seen than Dürer’s charts. However, one omission which would have made them less useful to serious astronomers is that Honter did not number the stars so they could easily be looked up in the Almagest, as Dürer had done.
John Seller (1632–97) was an English maker of charts and instruments, appointed hydrographer to King Charles II in 1671. With the help of Edmond Halley he published planispheres of the northern and southern sky and a set of strip charts of the zodiac in 1679. Halley was later to repeat the exercise with John Senex, using Flamsteed’s more accurate and extensive observations.
Johannes Honter’s celestial hemispheres of 1532 were the first printed star charts to show the sky from a terrestrial viewpoint, rather than as on a sphere. Like the Dürer maps before them, Honter’s hemispheres are centred on the ecliptic poles, not the celestial poles, so the constellations of the zodiac lie around the rim. Honter repeated the zodiacal figures on his southern hemisphere chart, which Dürer did not.
(Images courtesy Daniel Crouch Rare Books)
