Galileo’s telescope

Galileo Moon paintingGal

Galileo Moon painting

This article was commissioned by a noted British newspaper but never appeared, for reasons too dull to recount. It is for sale to any massively high bidder.

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It is 400 years since Galileo Galilei first pointed his telescope at the sky. His findings revolutionised the way we think about our place in the universe. But ironically, Galileo discovered the mountains of the Moon, the satellites of Jupiter, the stars of the Milky Way and the phases of Venus despite severe eyesight problems that would have driven most people to seek an alternative career.
Now scientists in Florence, where Galileo is buried in the Santa Croce church, plan to find out exactly what was wrong with his eyes. Their approach is a direct one. They want to dig him up, in the hope that his DNA will reveal all.
Almost any contemporary painting of Galileo suggests something odd about his eyes, which seem to be pointing in opposite directions. But Paolo Galluzzi, director of the Museum of the History of Science in Florence, points to other evidence of Galileo’s vision problems. His extensive correspondence with his family often discusses difficulties with his eyesight.
Professor Galluzzi explains that DNA evidence should make it possible to distinguish between competing explanations for Galileo’s vision trouble. One school of thought holds that he had a secondary glaucoma in which the sufferer loses vision across their whole eye uniformly: the other is a primary glaucoma which destroys the eyesight from the periphery inwards.
Galluzzi says: “Both of these types of glaucoma are related to genetic disease. DNA tests will tell us which type he had. And of course, they may reveal that he had neither of these conditions, which will mean we have to think again.”
Speaking last week in Stockholm, where one of Galileo’s two surviving telescopes is the centrepiece of a new exhibition on his work at the Nobel Museum, Galluzzi explained the many obstacles to digging up one of the most famous corpses in a church which also houses Marconi, Machiavelli and Michelangelo, and which is still in active use with about two million visitors per year.
He says: “The excavations we plan would take several months. The site is very sensitive and complex, and has been damaged by flooding. But before we can begin, we need to get permission from the Church, from the Italian ancient monument authorities, from the Ministry of the Interior, and from the health and safety experts, because we are planning to disturb a human body. We also need to choose our scientific partners and raise the money, about €300,000 (£281,000).”
The planned dig would be one of the few ever carried out with a specific person as its target, although a similar excavation has been done to investigate Galileo’s patrons the Medici. But Galluzzi and his colleagues already know that the grave contains more than one body. Galileo died in 1642 and was buried in a modest grave before being reinterred in his current sarcophagus in 1737. It took this long for the Catholic church to judge that a decent interval had elapsed since Galileo’s famous disagreement with Pope Urban VIII over the shape of the solar system.
Galluzzi says: “We know from contemporary records that the sepulchre contains at least one other body, that of a woman, and perhaps also a baby. We would be able to use DNA to find out whether the woman is related to him.” One possibility is that she is Marie Celeste, famous to modern readers from Dava Sobel’s book Galileo’s Daughter, who became a nun but remained close to her father.
The planned excavation would identify these relationships rapidly, and even shed light on Galileo’s vision problems. But Galluzzi adds that it would go on producing scientific papers and results for years. “As well as his vision, it would tell us about his severe rheumatism, the other diseases of Galileo and the other bodies in the grave, and even Galileo’s cause of death.”
Giorgio Strano, curator of the collections at the Florence Museum, says that digging up Galileo is only part of a wider plan to find out more about the scientist whom many regard as the founder of modern physics and astronomy. Another avenue is the study of his telescopes and his writings about them.
Strano says: “We know from Galileo’s extensive records that he made over 100 telescopes, for customers and for his backers and political patrons. But only two survive. The others were probably broken up because the lenses were so precious that they were reused. The lenses were such valuable craft objects that the makers who ground them sometimes signed them near the edge.” One who did so was Evangelista Torricelli, a near-contemporary of Galileo who is best known for his work on air pressure and vacuums.
As Galluzzi puts it: “Craftsmen of that age did not write about how they worked, because they wanted to keep their secrets. But we know a lot about their work from the instructions they wrote for the people who bought their telescopes, and the letters of dedication they addressed to the monarchs, ambassadors and others who received them.”
But two of Galileo’s telescopes do survive and are normally in the Florence Museum. They are exhibition-quality pieces made for his sponsor Cosimo II de Medici, the Grand Duke of Tuscany, and have been cared for throughout their lives. Modern technology has allowed the composition of the glass used in them, and the optical qualities of the lenses, to be determined so that exact replicas can be built.
It turns out that Galileo’s telescopes were less capable than even a modest modern telescope or binoculars. His contemporaries were often unable to see the things he tried to show them at the telescope. This behaviour has sometimes been attributed to bigotry. But it is likely that less skilled observers genuinely could not see objects such as the tiny moons of Jupiter, which Galileo discovered and wanted to call the Medicean Stars.
Strano says: “When we look at the sky through these replica telescopes we realise what a great observer Galileo was. For example, their field of view was so tiny that he could only have seen half of the full Moon at a time.” Despite this drawback, his watercolours of the lunar surface are artworks of exceptional beauty as well as being scientifically accurate.
According to Strano, Galileo was able to succeed as the first telescope-using astronomer because of his technological prowess as well as his scientific insight and his artistic ability. Only a year before Galileo started making and using telescopes in 1609, the Dutchman Hans Lipperhey had applied to a patent on the telescope. The Netherlands government rejected it because too many others were working on the same idea. He also tried a patent for binoculars. Galileo seems never to have tried making these, perhaps because he was unable to form an image with both eyes.
But the Dutch telescopes of the era were too poor to show the sky in detail. While they are crude by modern standards, Galileo’s telescopes were technologically advanced for their day. Galileo used better craftsmen, as well as making lenses himself, and bought better raw materials. A shopping list in the Stockholm exhibition includes mirror glass from Murano in Venice, known to be the highest-quality glass available.
Galluzzi says: “Like many scientists of that era, Galileo was also a craftsman. When he was a professor at Padua, he made telescopes for money. But when he became part of the Tuscan court, he had access to glass-blowers, metal workers and other skilled people and probably did less of the work himself.”

Galileo’s Telescope: The Instrument that Changed the World is at the Nobel Museum, Stockholm until January 17. It is sponsored by Italian watch maker Officine Panerai. Martin Ince visited the exhibition as a guest of Officine Panerai.

Galileo Moon painting

Galileo Moon painting