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".
Rangaku
Japan’s first telescope was offered by the English captain John Saris to Tokugawa Ieyasu in 1614, with the assistance of William Adams, during Saris's mission to open trade between England and Japan. This followed the invention of the telescope by Dutchman Hans Lippershey in 1608 by a mere six years. Refracting telescopes were widely used by the populace during the Edo period, both for pleasure and for the observation of the stars.