Telescope

A telescope is an optical instrument using lenses and/or curved mirrors to observe distant objects for both terrestrial applications and astronomy.

In 1608 a patent was submitted by Dutch spectacle maker Hans Lippershey for a refracting telescope. Galileo heard about it and, in 1609, built his own version, and made his telescopic observations of celestial objects. In 1668 Isaac Newton built the first practical reflecting telescope.

The 20th century also saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays. The first radio telescope went into operation in 1937. Since then, a large variety of complex astronomical instruments have been developed.