Galileo did not invent the telescope. He improved upon existing telescope designs.

The telescope was invented in the Netherlands around 1608, likely by Hans Lippershey or Zacharias Janssen. Galileo heard about this invention and, using his knowledge of optics, built his own telescope.

Galileo's version was significantly better than the Dutch telescopes, with a higher magnification and clarity. He used his improved telescope to make groundbreaking observations of the Moon, planets, and stars.