Huygens

Christiaan Huygens was one of the first astronomers to apply mathematical principles to the design of optics rather than trial and error, and his telescope could study Saturn's ring system. The Huygenian eyepiece he invented in the 17th century is still in use today

The mystery of Christiaan Huygens’ flawed telescopes may have been solved

Christiaan Huygens’ Telescope Lenses Tell Us He Was Nearsighted

The Sounds of Titan In 2005, the European Space Agency's Huygens probe descended to the surface of Saturn's moon Titan. Microphones aboard Huygens recorded the sounds of descent and landing.