This one to the left is the Galileo Refractor (c. 1609):
Though he didn't invent the telescope, Galileo improved on its design - gradually increasing its magnification power. And he was the first to realise that it could be used to study the heavens rather than just to magnify objects on Earth.
Here you can see Galileo demonstrating one of his telescopes to the ruler of Venice in August 1609 (Galileo is standing to the right of the telescope). In the years to come, Galileo's observations - including the discovery of four large moons orbiting Jupiter - would lend credence to the sun-centred worldview of Nicolaus Copernicus, who removed the Earth from its central position in the universe.