Sidereus Nuncius
The first telescopes appeared in the Netherlands in 1608 when Middelburg spectacle-maker Hans Lippershey tried to obtain a patent on one. By 1609 Galileo had heard about it and built his own improved version. He probably was not the first person to aim the new invention at the night sky but his was the first systematic (and published) study of celestial bodies using one. One of Galileo's first telescopes had 8x to 10x linear magnification and was made out of lenses that he had ground himself. This was increased to 20x linear magnification in the improved telescope he used to make the observations in "Sidereus Nuncius".
Optical microscope
Galileo Galilei is also sometimes cited as a compound microscope inventor. After 1610 he found that he could close focus his telescope to view small objects, such as flies, close up and/or could look through the wrong end in reverse to magnify small objects. The only drawback was that his 2 foot long telescope had to be extended out to 6 feet to view objects that close. After seeing the compound microscope built by Drebbel exhibited in Rome in 1624, Galileo built his own improved version. In 1625 Giovanni Faber coined the name "microscope" for the compound microscope Galileo submitted to the Accademia dei Lincei in 1624 (Galileo had called it the ""occhiolino"" or ""little eye""). Faber coined the name from the Greek words "μικρόν" (micron) meaning "small", and "σκοπεῖν" (skopein) meaning "to look at", a name meant to be analogous with "telescope", another word coined by the Linceans.