Galileo Galilei’s spotting scopes

The telescope is the astronomer’s principal system of observation. The earliest instruments in this family, the spotting scopes, were created at the end of the 16th century by Dutch craftsmen, but are little better than a curiosity, owing to their poor quality. At the beginning of the 17th century, Galileo Galilei was first to think of pointing a telescope toward the celestial vault—that curious collection of lenses capable of “bringing things closer”—for the purpose of investigating objects and astronomical phenomena more deeply, with new eyes. From that moment, the telescope became an actual scientific instrument, marking the birth of modern astronomy. Many instruments are based upon the principle of the refractor telescope introduced by Galileo’s spotting scope, in which a system of lenses collects and directs light toward the viewer, allowing observation of remote images. Today’s telescopes are reflectors: in place of lenses, they make use of mirrors, and the human eye is replaced by electronic detectors, allowing observation of ever more distant objects, in greater detail.