On this day in 1609 Galileo Galilei demonstrated his first telescope

Galileo Galilei

On this day in 1609 Galileo Galilei demonstrated his first telescope to Venetian lawmakers, including Leonardo Donato, the Doge (ruler) of Venice. At the time, Galileo taught geometry, mechanics and astronomy at the University of Padua, which was part of the Venetian republic. A year after the demonstration, he published Starry Messenger, which described his finding – made with his new telescope –that Venus and the moons of Jupiter have phases, like the Moon. Galileo recognized that his observations supported Nicolaus Copernicus’s theory that the planets revolve around the Sun. His advocacy of the theory culminated in 1632 with the publication of his Dialogue Concerning the Two Chief World Systems. The book and the surrounding controversy led to his conviction by the Roman Inquisition in 1633 of heresy. Galileo was held under house arrest until his death in 1642. Source: PhysicsToday

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4 Responses to On this day in 1609 Galileo Galilei demonstrated his first telescope

  1. alfy says:

    I wonder what the Doge was looking at in broad daylight? It would be nothing astronomical as the only thing visible would be the sun. Using a telescope on the sun would have burned the Doge’s eyeball out, if not the back of his skull. Perhaps he was viewing the dolly birds along the Riva degli Schiavoni outside his palazzo? I worry about the ornate telescope tripod, as it looks very close to falling off the edge of the little table.
    Nice picture, Jim; I wonder who the artist was?

    • Deskarati says:

      Just did a quick search and find that this is a fresco by Giuseppe Bertini (1825–1898) an Italian painter from Milan.

  2. Naan Glozi says:

    Hans Lippershey, the Dutch spectacle maker invented the telescope in 1608 with about 3 times magnification. This news travelled fast and it wasn’t long before Galileo heard about this while visiting Venice in May 1609 and set about understanding it. He did this quickly, and as he was in Venice at the time he had the basic glass lens shapes made at the little island of Murano near Venice famous for glass manufacture. He then set about hand grinding these lenses himself and setting them into a tube to make his telescope. His first telescope was much better than the one he had heard of with a magnification of about 10 times. He realised the importance of this device at Venice to see ships coming from the horizon hours earlier than by the naked eye and he sold it to the authorities. He then went onto improving his design until he had one with a magnification of around 30 times. This is the one he used to map Jupiter and Saturn’s moons.

    • Deskarati says:

      I had never heard of Hans Lippershey before Naan. So I just checked him out on wiki and it sounds like the early invention of the telescope could very interesting. Maybe a post for the future.

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