Scene 9: Presentation of the Telescope
In Scene 9 of the opera, Galileo presents his newest invention, the telescope, to three powerful noblewomen: Marie de Medicis, Maria Maddalena, and, as she is introduced with great aplomb, "our celestial Grand Duchess, Mother Madama Christina." At the ladies' urging, Galileo explains the inner workings of the instrument, and how he came upon the idea.
Grand Duchess Christina of Tuscany
Galileo had a long-standing relationship with the Medici family, of whom all three women were a part. From 1605 to 1608, the astronomer was the tutor of Cosimo II, son of Grand Duke Ferdinando I, and his Grand Duchess, Christina of Lorraine. Among other things, Galileo instructed the boy on the use of one of his inventions, a military compass, and afterward he published an edition of those instructions, in a limited run of 60 copies, dedicated to his pupil. Cosimo II and Galileo remained friends throughout Cosimo's life, through his ascent to Grand Duke in 1609 until his death from tuberculosis in 1621.
A year before Ferdinando's death, the Grand Duke required his son to marry Archduchess Maria Maddalena of Austria, in order to cement an alliance with Spain, where Maria Maddalena's sister was the incumbent Queen consort. Upon Cosimo's death in 1621, Maria Maddalena and her mother-in-law (the Duchess Christina) acted as co-regents until Cosimo's ten-year-old heir came of age.
Cosimo II's wife, Archduchess Maria Maddalena of Austria
As for Marie de Medicis (the French version of her name; in Italian she is known as Marie de' Medici): she was Cosimo II's cousin, and also just happened to be wife of King Henry IV of France, and, therefore, France's Queen consort.
Marie de Medicis
Got that? I had to draw a diagram to figure it out.
So, about that telescope. In 1609, news of a telescope invented by a Dutchman, Hans Lippershey, spread quickly through Europe. When Galileo heard of the invention, he immediately set to work trying to replicate it. His telescope used one convex lens and one concave lens, allowing the user to see the magnified image upright, whereas Lippershey's telescope, made of two convex lenses, transmitted the magnified image upside-down. The Venetian Senate had just convened to discuss purchasing Lippershey's telescope, but by enlisting his powerful friends to pull some strings, Galileo managed to slip his version into the Senate first. The instrument was crafted in a tooled leather case, and allowed the senators to see galleys on the horizon that did not become visible to the naked eye for another two hours. In a political stroke of genius, Galileo offered the telescope to the Senate for free, and was awarded tenure in his teaching post at Padua for life, at double his wages, bringing his yearly salary to 1,000 crowns.
So, just to be clear, although Galileo is commonly credited with invention of the telescope, he actually kind of ripped it off another guy. But Hans Lippershey likely didn't invent the first telescope, either, so don't feel too badly for him.
Despite its origin, it's what Galileo observed through his famous telescope that really matters:
• The four brightest moons of Jupiter, which he named "the Medicean stars," to honor the Medici family (although that didn't stick: now they're called the Galilean moons);
• The pock-marked face of the moon, with mountains, he calculated (by observing the terminator, the line separating lunar day from night) to be at least 4 miles tall. The discovery of the moon's craggy surface contradicted Aristotelian cosmology, which asserted that the heavens, which must be more perfect than the earth, were flat and utterly unblemished
• The Milky Way, which he discovered was not a solid object, but was in fact made of lots and lots of individual stars
Galileo published his findings in a booklet called The Starry Messenger, which had an initial run of 550 copies, and which was so successful that Galileo himself only managed to get 6 copies. He dedicated the work to Cosimo de' Medici. It has been described as the most important book of the seventeenth century.
The diagram of the optical principles of the telescope, from Galileo's book, The Starry Messenger.