Above Galileo the two putti illustrate two aspects of astronomy. The putto on the left holds a hinged rule with a quadrant arc, similar to a device invented by Galileo as a mathematical aid, and thus represents the traditional astronomy of charting stars. The putto on the right appears to be holding a telescope, albeit one that looks somewhat like a trumpet, and so symbolises the new astronomy of discovering stars with the telescope that Galileo had inititated. A few early telescopes are know to have been trumpet-shaped, including one now in the National Maritime Museum (NAV1547).

Originally the frontispiece to the collected works of Galileo.

The image was first used as the frontispiece to Galileo's 'Istoria e Dimonstrazioni intorno all Machie Solari' (Rome, 1613) and again for 'Il saggiatore' (Rome, 1623).