The Farnese collection at the Naples National Archaeological Museum is one of the finest collections of objects of Roman antiquity in the world. It is named for cardinal Alessandro Farnese (1520-1589), notable collector and patron of the arts. The collection was originally in Rome but passed to Naples when Elizabeth Farnese (1692-1766), the Queen Consort of Spain (wife of Philip V), who owned it by inheritance, passed it on to her son, Charles, who became the first monarch of the new Bourbon dynasty of Naples in 1735. The collection fit into Charles' plan to elevate the cultural level of the kingdom; this included building the San Carlo theater, opening excavation sites at Herculaneum, and, in this case, incorporating the considerable Farnese collection into a nascent museum at the northwest corner of the old city, premises that had originally housed a cavalry barracks and then the University of Naples.

Within that collection, one of the most interesting pieces and one that has attracted considerable scholarly debate is the so-called Farnese Atlas (photo). It is a 2nd-century Roman marble copy of a Greek sculpture of the Titan, Atlas, kneeling and holding the burden of the sky on his shoulders. The statue is seven feet tall (2.1 meters) and the globe just over two feet in diameter (65 cm); it is the oldest statue still in existence of Atlas, and the globe is the oldest known representation of the celestial sphere, the imaginary, rotating bowl of night above us that contains the stars we see. The Farnese globe shows at least 40 of the classical Greek constellations, the ones familiar to westerners: Aries the ram, Cygnus the swan, etc. etc. The statute dates to 150 AD but is believed to represent the constellations as they appeared to earlier Greek astronomers.

The extent to which the globe really does represent the constellations as seen by the ancient Greeks is at the heart of the debate. In 2005, Bradley Schaefer, a professor of physics at Louisiana State University concluded that the text of a long lost star catalog by Greek astronomer, Hipparchus, may have been the inspiration for the original statue. From analyzing the positions of the constellations on the globe, he concluded that they were consistent with how they were viewed at the time of Hipparchus (c. 130 BC); thus, he said, the Farnese globe is based on Hipparchus' star catalog. The popular press picked up the story and at least some accepted it uncritically. The New York Times said:

"Some historians had speculated that the sculptor might have consulted the work of Ptolemy, who lived about 250 years after Hipparchus, or Aratus, who described the constellations in a poem about a century before Hipparchus. Curiously, no one appears to have suggested Hipparchus' catalog as the reference source."

That is incorrect. The original idea was presented much earlier by Georg Thiele, a German scholar. He, indeed, suggested Hipparchus' catalog as the reference source. (In Antike Himmelsbilder [Ancient Constellations] by Georg Thiele, pub. Weidmann, Berlin, 1898.)

Hipparchus (c. 190 BC- c. 120 BC) is considered to be almost the founder of modern, accurate Western astronomy; he developed spherical trigonometry, for example, and for his star catalog, completed in 129 B.C., devised a coordinate system to plot each star's location and a scale to rank the brightness. He is also believed to be the one who discovered "precession," the exceedingly slow change in the position of astronomical bodies as seen from the earth due to the fact the earth, as it rotates on its axis, also wobbles like a top slowing down. The axis points north, yes, but slowly traces a gigantic cone in the sky as the earth "wobbles", completing one cycle every 26,000 years. That is why "north" and the "north star" shift over time and why the seasonal "reversals" of the sun known as the "equinoxes" shift ever so slightly over the centuries. As most know, the current north star is Polaris, the brightest star in the constellation Ursa Minor, also known as The Little Dipper. (Polaris is only about one degree off of the true north celestial pole, which is the axis of the earth extended into space.) Over the millennia, other stars have been "north" and, indeed, will be again some day. In the year 3,000 BC, the faint star Thuban in the constellation Draco had the honor, and if you can wait until the year 3000 AD, the honor of informing us which way is up will have passed to Gamma Cephei, also known by its Arabic name, Alrai, meaning "shepherd."

The recent resurrection of the idea that the Farnese globe is indebted to Hipparchus has attracted strong criticism. The globe contains no actual stars, just pictures of constellations, say critics, and the whole statue, in any event, was copied by a sculptor, not an astronomer; it is, at best, ambiguous. What's more, they say, at least some of the constellations, in fact, do not correspond to the night sky at the time of Hipparchus. Me, I don't know. I'll just sit here and quietly wait for the coming of the shepherd. He'll know.