![]() Still, this modest telescope was good enough to make discoveries as important as any in the history of astronomy.Īs most new stargazers do, Galileo began by studying the Moon. Its front lens was only 37 mm (1½ inches) in diameter, and the field of view was restricted to 15 inches at 100 yards - much narrower than most instruments now. By contrast to modern refracting telescopes, Galileo Galilei's instrument was not very capable. The newly promoted professor then made a 20-power telescope for his own use and began studying the night sky in October or November. Impressed, the senators doubled his salary and guaranteed his job for life! ![]() In August 1609 Galileo presented the Venetian Senate with an 8-power telescope. Several months later news of Lipperhey’s invention reached Galileo in Italy, who quickly fashioned an instrument of his own. It was a tube with a convex lens in the front and a concave lens at the eyepiece end, a combination that made distant objects appear much closer. In October 1608 a Dutch eyeglass maker named Hans Lipperhey filed a patent application for an invention he called a kijker (“looker”). Shown here is the skyward end of a museum-grade replica that, once completed, will be displayed at Griffith Observatory in Los Angeles.īut all that would eventually change. Only two of Galileo”™s many telescopes survive. ![]() It was a radical departure - most authorities continued to accept the Ptolemaic system. In 1543 Nicholas Copernicus published a fundamentally different concept that placed the Sun at the center of the universe with Earth and other planets moving in orbits around it. Of course, not everyone accepted the ideas of Aristotle and Ptolemy. Imagine the planets as perfect bits of aether instead of worlds with moons of their own. Try to see the stars not as distant suns, but as points of light shining from the edge of the universe. It takes a bit of imagination, but look up at the night sky and think about how it must have appeared to people who lived before Galileo. And, unlike earthly matter, the spheres and all they contained consisted of a perfect, changeless, and eternal “aether.” In the 2nd century AD, the influential astronomer-geographer Ptolemy introduced an even more elaborate crystalline-clockwork scheme that prevailed unchallenged for nearly 1,500 years. The spheres spun at various rates, such that the Sun completely encircled Earth in just one day while the stars took an entire year. In their view, Earth sat motionless at the center of the universe, with the Sun, Moon, planets, and stars affixed to nested crystalline spheres like the layers of an onion. ![]() As you “rediscover” some of the night sky’s many marvels, you’ll gain skill as an observer and get an appreciation for the profound insights revealed to Galileo’s inquisitive eyes.īefore the telescope came along, most educated people still accepted concepts about the universe first popularized by Aristotle and his contemporaries in the 4th century BC. You can follow the same path as Galileo Galilei, observing the same celestial sights that he did - from craters on the Moon to the miniature solar system encircling Jupiter. All the unexpected sights revealed through his instrument transformed his life and the world at large. But four centuries ago the telescope was a revolutionary new invention, and when the great scientist Galileo Galilei first pointed a telescope skyward in late 1609, he was astounded by what he saw night after night. Although spotting some never-before-seen celestial object can happen, it’s rare these days because so many professional and amateur astronomers are combing the sky every night. Imagine the thrill of looking through a telescope and making a new discovery as soon as you peer into the eyepiece. Portrait of Galileo Galilei, from the National Maritime Museum, London ![]()
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