Cerberus was the triple-headed monster that guarded the gates of Hades, the realm of the dead, preventing the living from entering and the dead from leaving. As the last and most dangerous of his 12 labours Hercules was sent to the Underworld to capture this fearsome beast. He wrestled the creature into submission with his bare hands and dragged it, writhing and resisting, from the darkness of the Underworld to the unaccustomed brightness of the surface. The constellation commemorating this feat was added to the sky by Johannes Hevelius in his catalogue and atlas of 1687 in which he depicted Cerberus grasped in the outstretched hand of Hercules.
Cerberus consisted of the four stars we now know as 93, 95, 102, and 109 Herculi (R. H. Allen wrongly states 96 Herculi to have been a member). Although, in mythology, Cerberus was said to be a three-headed dog, Hevelius and all subsequent map makers illustrated it with three snake heads.
Hevelius’s Cerberus replaced another figure, the branch from the tree of the golden apples, that Johann Bayer had previously depicted in the hand of Hercules. Bayer’s elaborate apple branch consisted of 10 stars. (Incidentally, R. H. Allen in his book Star Names says that Bayer called the apple branch Ramus Pomifer, but I can find no mention of it in Bayer’s Uranometria; rather, the name Ramus Pomifer seems to have arisen with Alexander Jamieson on Plate 8 of his Celestial Atlas of 1822.)
In or around 1721 the English cartographer and engraver John Senex (1678–1740), a friend of Edmond Halley, combined Cerberus with Bayer’s apple branch to produce what he labelled Ramus Cerberus. This combined figure first appeared on Senex’s chart of the northern celestial hemisphere, Stellarum Fixarum Hemisphaerium Boreale, which he produced from Halley’s pirate edition of Flamsteed’s unfinished star catalogue. Johann Bode subsequently showed them on his Uranographia atlas of 1801 under the name Cerberus et Ramus (see illustration below). However, Flamsteed’s own chart of Hercules, published in his Atlas Coelestis of 1729, includes neither Cerberus nor Ramus; instead, Hercules is drawn simply grasping thin air.
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Cerberus held in the grasp of Hercules, as shown on the Firmamentum Sobiescianum star atlas of Johannes Hevelius (1687). It is drawn in mirror image, as it would appear on a celestial globe. Image courtesy ETH-Bibliothek Zurich.
Cerberus et Ramus, the three-headed monster entwined with an apple branch,
shown on Chart VIII of the Uranographia of Johann Bode (1801).