Ptolemy Tilted Off His Axis

In a sunlit gallery of the Museo Archeologico Nazionale in Italy, astronomer Brad Schaefer came face to face with an ancient statue known as the Farnese Atlas.

For centuries, the 7-foot marble figure of the mythological Atlas has bent in stoic agony with a sphere of the cosmos crushing his shoulders.

Carved on the sphere -- one of only three celestial globes that have survived from Greco-Roman times -- are figures representing 41 of the 48 constellations of classical antiquity, as well as the celestial equator, tropics and meridians.

Historians have long looked on the Atlas as a postcard from the past -- interesting largely as astronomical art.

But as Schaefer approached, he began to notice subtle details in the arrangement of the constellations. It wasn’t that anything was wrong with the statue. If anything, the positions of the constellations were too perfect to be mere decoration.

He was more than a little intrigued. No, this was no mere piece of art. Taking out his camera, he was about to take a journey through the centuries to unravel one of the great mysteries of the ancient world and uncover key evidence in what may be one of the biggest cases of fraud in the history of science.

*

You might call Brad Schaefer a detective to the stars.

That’s Antares, not Aniston. Betelgeuse, not Michael Keaton.

When Schaefer’s not cramming Astronomy 101 into his students at Louisiana State University in Baton Rouge, he is chasing his quarry across the starry landscape like a celestial Sherlock Holmes.

Over the course of his career, he has written more than 250 articles on such quirky subjects as how the stars influenced Egyptian civilization and why people seem to kill themselves when Halley’s comet comes around.

“I like to tell stories,” he said.

Dressed casually in tennis shoes and loose clothing, he looks younger than his 48 years. Backyard inventor, chess expert and former world-ranked tiddlywinks player, the MIT graduate can seem the stereotypical absent-minded professor and perpetual adolescent.

But behind that mop of blond hair and the twitchy mannerisms is the bulldog temperament of a big-city homicide detective.

A few years ago, he decided to try to determine the actual date of Christ’s Crucifixion using purely scientific methods. He wrote a computer program that factored in all the astronomical data he could unearth from the time. Then, because the Crucifixion is thought to have taken place 14 or 15 days after a crescent moon first became visible, he added in thousands of modern records of atmospheric haze to approximate periods of high and low visibility in the ancient Middle East.

Rolling back the calendar more than 1,900 years, he came up with two dates: AD 30 and 33.

Bible scholars, comparing biblical texts with historical records, have arrived at similar dates.

Schaefer thinks his results are more reliable. “People in the past never tried doing physics-based research,” he said.

Schaefer wasn’t looking for another mystery when he and his wife, a planetary geologist, took a Mediterranean cruise in June.

The purpose was to view the transit of Venus -- a rare astronomical event in which the planet crosses the face of the sun.

Schaefer decided to pay a visit to the Museo Archeologico Nazionale in Naples.

He knew something of the Farnese Atlas, named for Cardinal Alessandro Farnese, who purchased it in the 16th century. The statue, probably a Roman copy made about AD 150 of an earlier Greek statue, is the oldest representation of the original Western constellations.

There are no stars on the globe, just the constellations themselves, represented by earthly forms such as a ram, a bull or a huntsman. Even so, he could tell that they were laid out with great precision. If the globe was accurate, he realized, the heavenly scene depicted on its surface would conform to only one moment in history. And thus reveal for the first time its origins.

But how to find that moment? It wasn’t as simple as rewinding the celestial clock. This time, he had to guess the position of the stars within those earthly forms, from the position of a horn or a hoof.

Few astronomers would have thought it possible.

To Schaefer, that just made the task more interesting. He returned to Louisiana to begin the painstaking work of finding his way back through the fog of time.

In antiquity, man tried to make the night sky familiar by stitching stars into constellations.

Mesopotamians created zodiac signs as early as 1100 BC. Some Chinese constellations are 2,000 years older than that.

The world’s oldest constellation is thought to be the Big Bear, which we know as the Big Dipper. Schaefer traced it to an Ice Age bear cult from 14,000 years ago.

A few hundred years before Christ, a handful of stargazers began looking beyond the pictures in the sky to the actual mechanics of the cosmos.

The most famous of the ancients was Hipparchus, born in what is now Turkey in 190 BC. He calculated the length of a year to within 6 1/2 minutes and was the first to explain the Earth’s rotation on its axis. He also compiled the first comprehensive catalog of the stars.

Today, only one work by Hipparchus remains, his Commentary, a criticism of an earlier poet-astronomer, Aratus. Everything else, including his famed star catalog and globe, was presumed lost in the great fire that consumed the Library of Alexandria sometime before AD 400.

Looming over the ancient scientists like the Colossus of Rhodes is Claudius Ptolemy, who is still studied in modern classrooms as one of the greatest scientists of all time.

About 250 years after Hipparchus, Ptolemy charted the positions and movements of a thousand stars, as well as the motions of the sun, the moon and the planets out to Saturn. His most famous work, the Almagest, roughly translated as “the Greatest Compilation,” was published around AD 128 and became one of the most influential scientific texts in history.

Despite being wrong about the Earth being the center of the universe, the Almagest was the final word on the comings and goings of the stars for 1,400 years.

Ptolemy was not dethroned until the 16th century, when Copernicus determined that the Earth traveled around the sun.

At that point, critics began to reevaluate Ptolemy. His math was suspect, they said. Some of his findings were flat-out wrong. Those that weren’t wrong, they suspected, had been pilfered. Some scientists and authors wondered openly what once would have been considered blasphemy: Had Ptolemy stolen his masterwork from someone else? Perhaps from Hipparchus?

The fight continues today. Robert Newton, in his 1977 book “The Crime of Claudius Ptolemy,” called him “the most successful fraud in the history of science.”

In the usually restrained world of astronomy, passions ran high at a 1999 debate at the University of Notre Dame. Advocates agreed that Ptolemy borrowed liberally from Hipparchus and others, but they said plenty of scientists did that.

“Some want to make it a moral issue,” said James Evans of the University of Puget Sound.

“To impose on the ancients the same standards we expect today is a little naive.”

Rubbish, say critics. This is no minor tinkerer. This is one of the world’s most illustrious scientists who could be a faker. A crime of that magnitude should not stand.

“Ptolemy stole, fabricated and mutilated data,” thundered the International Journal of Scientific History.

“The Ptolemy-Hipparchus feud has led to many unprofessional acts,” Schaefer wrote in a 2002 article in Sky & Telescope magazine. “These include shunning of people at conferences and spammed hate mail.”

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Schaefer knew as he began work in Louisiana that the Atlas was a scientific instrument. But on whose vision was it based?

Among the candidates were Ptolemy, Hipparchus and a variety of other ancients, including the Greek astronomers Eudoxus, Aratus, Eratosthenes, an unknown ancient Assyrian, even Homer. Perhaps it was someone unknown to the modern world.

The first step was dating the statue. Despite a hole in the top that obliterated Ursa Minor and Ursa Major, the globe provided several hints that quickly placed an upper date on the sculpture.

It was missing the later-devised Greek constellations of Equuleus, Coma Berenices and Antinous. Hercules is also depicted as a kneeling, naked man instead of as a hero, as in latter Greek times.

One last tip placed the sculpture well before Ptolemy. The carving of Aquarius on the Atlas contained the outline of a water jar. In the Almagest, Aquarius has no water jar.

The answer had to lie deeper in the past.

One clue put a lower limit on the star chart. The summer solstice on the statue is shown at the start of Cancer. Eudoxus and Aratus, who lived before 245 BC, described it as being in Leo. But that could not be, because the solstice, which gradually moves through the centuries, hadn’t been in Leo since 1250 BC. Schaefer also noted that the head of Andromeda did not overlay the navel of Pegasus, as it would have in the time of Eudoxus and Aratus.

All this placed the star map between Eudoxus and Aratus, and Ptolemy -- roughly 245 BC to AD 200.

Hipparchus lived in that time. Schaefer’s excitement rose. He turned to Hipparchus’ sole surviving work, the Commentary, which contained enough specific references to stars for a comparison with the statue.

He soon discovered a surprisingly exact match: The positions of Auriga the Charioteer, Centaurus and Draco all matched Hipparchus’ descriptions.

When he was done comparing 70 different points on the globe with the ancient records, Schaefer produced a date of 125 BC.

“This is just when Hipparchus was flourishing,” he said.

Just to be safe, he did one more analysis to find out where the original observer lived.

A latitude could be estimated, he figured, by noting the declination of the Arctic and Antarctic circles.

Based on the estimated Arctic circle declination, Schaefer came up with possible latitudes of the observer of from 34 degrees to 38 degrees, which encompasses the area where Hipparchus lived.

There was no doubt in Schaefer’s mind -- he had the lost star catalog of Hipparchus.

The solution to the mystery, Schaefer said, “was before our eyes the whole time.... [We] have recovered one of the most famous known examples of lost, ancient wisdom.”

Why had it taken so long to decode the Farnese Atlas?

Perhaps no one had thought to do the detailed calculations or had the obsessive patience to push through to the end.

“I think it’s amazing what he’s done,” said Owen Gingerich, a retired professor of science history at Harvard University and an author of books on ancient astronomy.

“There were no stars on the Atlas. He had to do it with horns and legs and noses.”

Hipparchus Ascendant

In January, Schaefer unveiled his findings at the winter meeting of the American Astronomical Society in San Diego.

“We have books like ‘The Da Vinci Code’ about a hero who discovers lost, ancient secrets. There are very few instances where lost secrets are actually found,” he said. “This is one.”

His findings were generally met with approval by colleagues.

“It seems a very valid conclusion,” said Hugh Thurston, a retired history professor from the University of British Columbia.

The discovery hit the popular media, both here and abroad. Schaefer’s findings are scheduled for publication in the May issue of the Journal for the History of Astronomy.

But his discoveries revealing the full genius of Hipparchus are rekindling the debate over Ptolemy.

Should he at last be thrown down and Hipparchus raised in his place?

Some advocate a measured approach. “I think Ptolemy ought to lose a bit and Hipparchus gain a bit,” Thurston said.

But even staunch Ptolemy supporters are reconsidering.

“This new information which Bradley Schaefer brought us will be grist for the mill for the battle to be waged,” said Gingerich at the San Diego conference.

“I may have to do a little rethinking about who was the greatest astronomer,” said the onetime Ptolemy supporter.

The feud holds little interest for Schaefer, who has moved on. The National Science Foundation has given him a grant to review 156 years of sunspot records.

The goal? To find out if the sun has a role in global warming.

Because the count is based on figures supplied by as many as 90 worldwide observers every year, the research is daunting. And mind-numbingly arcane. Schaefer doesn’t seem to notice.

He’s already uncovered mistakes, he said, a twinkle in his eye.

“I have a solution.”