History of the telescope
The earliest known telescope appeared in 1608 in the Netherlands when an eyeglass maker named Hans Lippershey tried to obtain a patent on one. Although Lippershey did not receive his patent, news of the new invention soon spread across Europe. The design of these early refracting telescopes consisted of a convex objective lens and a concave eyepiece. Galileo improved on this design the following year and applied it to astronomy. In 1611, Johannes Kepler described how a far more useful telescope could be made with a convex objective lens and a convex eyepiece lens and by 1655 astronomers such as Christiaan Huygens were building powerful but unwieldy Keplerian telescopes with compound eyepieces.
Linden Observatory Complex
Up until the 17th century, astronomy was positional and depended on observations of the naked eye. In the early 17th century a new instrument, the telescope was invented by Hans Lipperhey and quickly taken up and improved upon by Galileo Galilei. In 1610, armed with his 20 XX refractor telescope, Galileo discovered four moons of Jupiter and for the first time in the history of the world observed the movement of a satellite around a planet. Using his telescope Galileo also observed that the phases of Venus were similar to lunar phases and argued that these observations empirically supported the theory that the earth moves around the sun.