What optical device is the Dutch scientist, after whom the lunar crater Jansen is named, credited for?
Zacharias Janssen Zacharias Janssen (also Zacharias Jansen or Sacharias Jansen) (1585 – pre-1632) was a Dutch spectacle-maker from Middelburg associated with the invention of the first optical telescope. Janssen is sometimes also credited for inventing the first truly compound microscope. However, the origin of the microscope, just like the origin of the telescope, is a matter of debate.
Uraniborg Uraniborg (Danish: "Uranienborg" , Swedish: "Uraniborg" ) was a Danish astronomical observatory and alchemical laboratory established and operated by Tycho Brahe. It was built  1576 – c. 1580 on Hven, an island in the Øresund between Zealand and Scania, which at that time was part of Denmark. Shortly after its construction, the observatory was expanded with an underground facility, Stjerneborg, on an adjacent site.