The Medicean Stars is the name that Galileo gave to his discovery of the four largest moons that orbit Jupiter. He named them Io, Europa, Callisto and Ganymede. They are better known as Galilean moons or the Moons of Jupiter. Read about them below and see photos and a video.
Medicean Stars
The telescope was invented in the Netherlands during Galileo Galilei’s lifetime. The great mathematician of the middle ages heard of the telescope and immediate saw a good use for it. He studied the geometry of the concept and made himself one. He presented his first telescope to Italy to be used to see great distances at sea. But then he made himself one and used it to study the heavens.
It was with this new invention that Galileo discovered the moons of Jupiter in January 1610. There are actually 63 moons that orbit Jupiter. But the four largest of those moons were the first objects in the heavens that were discovered that orbited something other than the Earth or the Sun. It was a great discovery.
Galileo made good use of his discovery. He wanted to return to Tuscany. What better way to win the favor of the ruler of the region than to name his new discovery for the Grand Duke and his four sons? So that’s what he did. He named Jupiter for the Duke of Tuscany, Cosimo II de’ Medici. Thus, the Medician Stars! He named the moons for the Grand Duke’s four sons. The Grand Duke’s oldest son, Cosimo, had just ascended to be the Grand Duke. That all worked out quite well for Galileo.
Serenissimo Grand Duke, “scarcely have the immortal graces of your soul begun to shine forth on earth than bright stars offer themselves in the heavens, which, like tongues [longer lived than poets] will speak of and celebrate your most excellent virtues for all time.”
Don’t you love the way they talked back in the Middle Ages!
Of course, as with most things, there are less interesting explanations for the naming of the stars. Its also asserted that he simply named them after his patrons. Grand Duke Cosimo was a patron of literature, art and Galileo.
You might also note that during the period of time that Galileo was studying the stars the Grand Duke of Tuscany was Cosimo. Which explains why we call the universe the cosmos.
During his lifetime, The Moons of Jupiter were known as the Medicean Stars. Long afterward, they became known as the Galilean moons or Galilean Satellites, honoring Galileo himself.
Medicean Stars - Photos
Medicean Stars - Video