As author Fred Watson describes in his book Stargazer (2004), by mid-1609 Galileo had heard rumors about the new Dutch spyglass patented by Hans Lippershey called a "perspicillum" (from the Latin perspicax, "sharp-sighted"), although it is unlikely that Galileo saw a prototype. Being a mathematician, he deduced that the necessary magnification "was the result of the ratio of the focal length of the two lenses." Galileo soon found his own set of preexisting glass lenses and placed them at the right distance from each other in a lead tube. He used soft lead because it could be easily rolled and manipulated to hold the lenses securely. Galileo's telescope used one convex lens, called an objective, which gathers the light coming from the observed object, and one concave lens, the eyepiece; together, these lenses could magnify usually no more than three times. That year, Galileo steadily experimented by producing the shallow parabolic curves needed on glass lenses. Improving on the grinding and polishing of his own lenses and experimenting with the shallow angles and variable distances between the lenses, Galileo soon improved this magnification to twenty times and ultimately to thirty times.

Whereas others had primarily used the telescope for land viewing during the day, Galileo applied the new instrument heavenward at night. Viewing the Moon, probably for the first time ever at such clarity, Galileo noticed its rough spherical surface, pitted with craters and likely chasms. He soon made other important discoveries about the phases of Venus, Jupiter's four largest moons, the Milky Way as a mass of stars, and other astronomical phenomena he quickly published in his Sidereus nuncius (starry messenger) in early 1610.

Free term papers are not written to satisfy your specific instructions. You can use our professional writing services to buy a custom written research paper, term paper, or essay on Science at affordable price. CustomTermPapers is the best solution for those who seek help in writing term papers, essays, and research papers related to Science and other relevant topics.