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.
Steinheil (crater) Steinheil is a lunar impact crater that is located in the rugged highlands in the southeastern part of the Moon. It forms a prominent crater pair with the similar-sized Watt, which it partly overlies to the southeast. To the northwest is the large walled plain Janssen. Due to the location of this crater, it appears foreshortened when viewed from the Earth. It is from the Nectarian period, 3.92 to 3.85 billion years ago.