A half-length portrait, in old age, of the Italian mathematician, philosopher and astronomer, who was appointed court mathematician to the Medici dukes of Tuscany at Florence in 1610. He is dressed in black, wears a white beard and is seated in a chair holding a telescope in his right hand. His left hand rests on the arm of the chair and he wears a ring with a clear stone on his fourth finger. He faces forward towards the viewer. Galileo, though not first inventor of the refracting telescope in 1609, enhanced its power, which enabled him to see that the Moon had mountains and that Jupiter had satellites. His championship of the Copernican (Sun-centred) planetary system brought him into serious conflict with the Roman Catholic Church, which forced him to make a public recantation and put him under restriction in later life.