IN 1633, for his revolutionary discovery that the Earth revolves around the sun, Galileo Galilei was convicted by the Roman Catholic Church of holding views contrary to Scripture, arrested and imprisoned for life.

   It wasn’t until 1992 that the Vatican formally admitted that Galileo was correct. Four centuries after his great discoveries made with the telescope, the United Nations has proclaimed 2009 the International Year of Astronomy, a global celebration of the field’s contributions to society and culture.

   Called “the father of modern science” by Albert Einstein, Galileo didn’t officially invent the telescope but improved its magnification and was the first to train it on the stars for science. His discoveries in the sky include the phases of Venus and the four largest moons of Jupiter. He was the first to observe the mountains of the moon and analyzed sunspots.

   Quite literally a “Renaissance man,” the Tuscan physicist, mathematician, astronomer and philosopher penned Starry Messenger, a 17th century bestseller, and remade modern thought.

   To honor the 400th anniversary of his discoveries, the Franklin Institute in Philadelphia is exhibiting Galileo, the Medici and the Age of Astronomy through Sept. 7. “The International Year of Astronomy is an extraordinary opportunity for astronomers everywhere to present astronomy to the global community and encourage people around the world to experience the sense of discovery and excitement that comes from observing the wonders of the universe,” says Derrick Pitts, chief astronomer of the Franklin Institute who has been named U.S. spokesperson for the IYA.

   When the Franklin learned that the museum in Florence, Italy, that houses the Galileo telescopes would be closed for renovations this year, it campaigned successfully to create this exhibition.

   Upon hearing the science museum was going to be the sole exhibitor of Galileo’s telescope, I took my son, a doctoral candidate in astronomy at Cornell, and my husband, a science teacher, to the city Founding Father Franklin had a major hand in shaping. Dazzled by the brass and gilt instruments on display, we were somewhat letdown by the very plain appearance of the 400-year-old scope with Galileo’s handwriting on it. Made of varnished paper and copper wire and displayed in a Plexiglas case, it looked like a worn cardboard tube kids use as a toy megaphone.

   Not to worry, my son pointed out another of Galileo’s telescopes, this one of gold-embossed leather that he’d made for the Medicis. This wealthy and powerful Florentine family, known for its unparalleled advocacy and patronage of art and science, ruled from the 15th to the 18th century. They were prolific collectors of paintings, prints and manuscripts as well as scientific instruments. In fact the Uffizi Gallery in Florence was constructed in 1560 to house the collection.

   Florence was the epicenter of the Renaissance, with its advances in arts, science and engineering that remade medieval society and established the modern foundations of painting, sculpture, architecture and astronomy. Leonardo da Vinci, Michelangelo, Brunelleschi and Galileo made their contributions when the realms of art and science were entwined. Michelangelo was trained in engineering, architecture, mathematics, anatomy, painting and sculpture. Learned men were expected to use scientific instruments such as a compass, armillary sphere or astrolabe. Cosimo I, Grand Duke of Tuscany, surrounded himself with these people for the glorification of Florence and the Medici family.

   The instruments in this collection, designed not only for their function but with delicate craftsmanship and beauty, were used for exploration, surveying, construction of military fortifications, as well as perspective drawing, painting and architecture.

   Astrolabes are portable astronomical calculators that were used to tell time, rising and setting times of the sun, and rising and setting times for a number of fixed stars. In use in Arabic cultures since the 4th or 5th century, astrolabes are often inscribed with geometrical and astronomical tables. Astrology played a significant role in the decision making during this era, and the astrolabe could be used to interpret one’s horoscope.

   An armillary sphere is essentially a 3-D version of the astrolabe, first developed in Asia in the 4th century BCE and in use in Europe by the 10th century. Somewhat like a brass gyroscope, it is a model of planetary positions and motion in the solar system — the rings represent the planets, sun, moon and stars.

   The manufacture of all these instruments constituted a craft industry. In 1561, a survey ordered by Cosimo I, Grand Duke of Tuscany, found 2,182 workshops in Florence, including goldsmiths and braziers, gold beaters, scissors makers, leather manufacturers, clock and scale makers, spectacle makers, turners and bookmakers. A polyhedral dial, a sundial with nine different faces, is an example of how science and artistry fused, creating finely ornamented scientific instruments.

   The exhibit combines displays of these ancient tools with modern interpretations: Some old leather-bound, gilt-edged books behind glass, for example, are shown alongside a video that leafs through pages, enabling us to see inside the book without damaging its fragile pages. A reproduction of the frescoed ceiling of the mathematics room of the Uffizi shows everything from “Albrecht Durer’s Window” to terrestrial globes, surveying compasses, an hourglass and mining lamp, all in a concentric design.

   Fascinated by a Dutch spy glass, Galileo dedicated himself to improving its power of magnification. Through it he was able to see the individual stars, invisible to the naked eye, in the cluster of the Milky Way. He saw the crust of the moon and understood these were craters and valleys. Using Pythagorean Theory, he could calculate the height of these mountains.

   Galileo, an instructor to Cosimo II who sold compasses and instruction manuals, knew the Medici family could help him conduct experiments in physics exclusively, freeing him from having to teach, and the telescope was his entrée. The Medicis, who themselves had risen from the merchant class by their business acumen, awarded Galileo a lifetime salaried position as mathematician and philosopher to the court. Galileo named the moons of Jupiter the Medicean stars.

   Even after his ecclesiastical condemnation in 1633, Galileo still built the best telescopes on the market, the only ones suitable enough for serious scientific work.

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  Galileo, the Medici and the Age of Astronomy is on view at the Franklin Institute, 222 North 20th St., Philadelphia, though Sept. 7. Tickets, timed and dated, cost $20.75 adults, $19.75 students, seniors, military, $14 children. Hours: Daily 9:30 a.m.-5 p.m. Advance purchase recommended. 215-448-1200; www.fi.edu