The telescope’s invention has been attributed to several individuals, but, whatever its precise provenance, the scope quickly diffused throughout Europe and became the chief device by which astronomers such as Galileo, especially early on, explored the previously unseen wonders of the universe.

Ancient and medieval astronomers used instruments to map the positions of stars and to follow the paths of planets through the heavens, but these instruments were limited because all of them relied on the human eye unaided by any optical device. The magnifying power of lenses had been observed in the Middle Ages, and by the thirteenth century convex lenses were being used as reading glasses. Several medieval natural philosophers speculated about the possibility of using such lenses to enlarge distant objects, but these speculations did not result in practical instruments. [kw]Invention of the Telescope (Sept., 1608)
[kw]Telescope, Invention of the (Sept., 1608)
Science and technology;Sept., 1608: Invention of the Telescope[0500]
Inventions;Sept., 1608: Invention of the Telescope[0500]
Astronomy;Sept., 1608: Invention of the Telescope[0500]
Netherlands;Sept., 1608: Invention of the Telescope[0500]
Telescope;invention of

By the sixteenth century, Tycho Brahe, Brahe, Tycho the greatest observer of the heavens to work without an optical device, continued to make use of such apparatus as astrolabes, quadrants, and armillary spheres, although his instruments were larger and much more sophisticated than their medieval predecessors. The German astronomer Johannes Kepler Kepler, Johannes used Brahe’s precise data on Mars to discover that it, like the other planets, orbited the sun in elliptical, not circular orbits, thus helping him, without the aid of a telescope, to revolutionize astronomy.

Much controversy exists over the questions of where, when, and by whom the telescope was first invented. Claims have been made for Leonard Digges in England, Giambattista della Porta in Italy, and James Metius (also known as Jacob Adriaanzoon) in Holland, but scholars have found these affirmations, often put forward by relatives or friends of the claimants, are often unsubstantiated. Most historians of science and technology make Holland the country of the telescope’s origin and 1608 as the year of its development.

Dutch lens grinder Hans Lippershey is credited with the invention of the first telescope.

(Library of Congress)

Persuasive documentary evidence exists for a Dutch genesis of this invention, though some uncertainty exists about the actual inventor. These uncertainties are further complicated by the debate over what constitutes the “discovery” of this instrument. Is it finding that two lenses that are held an appropriate distance apart magnify distant objects? Or is it the actual construction of what would later be called a “refracting telescope” by fitting two lenses into a tube in which one lens (the objective) collects light and brings it to a focus while a second lens (the eyepiece) becomes the conduit of the magnified image to the observer?

Although most scholars credit Hans Lippershey Lippershey, Hans with the telescope’s discovery, the evidence for this attribution is not as unequivocal as scholars would like. Characterized by some as an illiterate artisan, Lippershey was a master of the techniques of lens grinding, for he was a successful maker of spectacles. In the traditional story, which has several versions, either an apprentice or two children, while playing with long and short focus convex lenses, noticed that the lenses, when held a certain distance apart, made the weather vane on a church across the street they were on appear larger and closer. Upon his return to his shop, Lippershey, when informed of this exciting observation, verified it, and then arranged the lenses in a metal tube, in effect creating the first refracting telescope.

Unlike other claimants for the glory of the telescope’s discovery, Lippershey, realizing its potential military value, quickly applied for a patent. On September 25, 1608, a committee of councilors in Zeeland wrote a letter to the States-General in The Hague, informing this governing body of The Netherlands that Lippershey had invented a device by means of which things at a great distance could be seen as if they were nearby. On October 2, 1608, Lippershey formally petitioned the States-General for a thirty-year patent for what he called a kijker (looker). Because of its potential utility for Dutch naval security, Lippershey requested that his invention be kept secret. He wanted an annual pension to enable him to manufacture these devices, which he promised to sell only in Holland. Prince Maurice of Nassau Maurice of Nassau , head of the Belgian army, tested Lippershey’s monocular instrument from a tower on his palace and declared that it would be of value to the Dutch state, especially if a binocular version could be built.

The telescope proved to be too valuable an invention (and too easy to duplicate) to remain a secret for long. In Alkmaar, about 20 miles north of Amsterdam, James Metius Metius, James sent a petition to the States-General in which he claimed that he had made a magnifying device equal in power to Lippershey’, but his request for a patent was denied, and his case for having invented the telescope independently of Lippershey was weakened by his refusal to show his device even to his closest friends.

Another possible Dutch inventor of the telescope, at least according to his son, was Zacharias Janssen Janssen, Zacharias who, like Lippershey, was an optician in Middleburg. Long after Zacharias Janssen’s death, his son claimed that his father had invented the telescope in 1590, but according to some scholars’ estimate of the father’s birth date, this would mean he invented the telescope when he was just ten years old, and just two years old if, as some believe, he was born in 1588. According to his daughter, Zacharias Janssen invented the telescope in 1611 or 1619, several years after Lippershey’s documented discovery. Some scholars think that the children may have confused their father’s invention of the microscope with the invention of the telescope. Zacharias Janssen led an unconventional life. He was convicted twice for counterfeiting and was forced to flee when his conviction resulted in a sentence of death by immersion in boiling oil. Research indicates that he never sought credit for the telescope’s discovery and this false claim was mainly his son’s doing.

Because the States-General declined to grant a patent to Lippershey, he saw his invention spread to France, Germany, and Italy without any remuneration coming to him. These instruments were called optic tubes, Dutch cylinders, optic glasses, or Dutch perspectives (the term “telescope” was a later, Italian coinage). Early in 1609, the telescopes were on sale in Paris and, later that year, they were being sold in Germany at a Frankfurt fair.

In Italy, Galileo Galileo;telescope first heard of Lippershey’s invention in May of 1609. Not only did this forty-five-year-old professor of mathematics re-create the Dutch invention, he was also able to make advanced models with greater magnifying powers than Lippershey’s device. His gift of a telescope to the Paduan senate resulted in a substantial salary increase for him at his university. So famous were the Galilean telescopes that he was often referred to as its inventor, an appellation he himself always denied, reserving that title for “the Dutchman.” However, he did claim for himself the serious, extensive, and intelligent use of the device to make many important astronomical discoveries.

Early in 1610, he found that his telescope revealed that the Moon, like the Earth, had mountains and plains (which he named “seas”) and, unlike the Earth, numerous craters. He found that the Milky Way was not a cloud but myriad unknown stars. He was the first to behold Jupiter’s spherical shape and its four satellites (now called “Galilean Moons” in his honor). He was also the first to bring to light the phases of Venus, which he used to support his longstanding belief in the Copernican heliocentric system. His publication of the Sidereus nuncius (The Sidereal Messenger
Sidereal Messenger, The (Galileo) , also known as The Starry Messenger) in March of 1610 made his telescope discoveries famous not only in Italy but in other countries as well.

In Germany, Johannes Kepler, who read and wrote about Galileo’s book, invented a new type of telescope that he described in his Dioptrice
Dioptrice (Kepler) (partial translation of the preface, 1880) in 1611. The Keplerian telescope came to dominate astronomy for more than a century.

The history of astronomy has been heavily populated with instruments, but none of these has had the dramatic and dominating influence of the telescope. Many scientists date modern astronomy from 1610, the year Galileo turned his telescope toward the heavens and expanded manyfold the frontiers of the observable universe. Astronomy;Europe

Early telescopes were hampered by chromatic and spherical aberrations, in which white objects appeared colored and out of focus, but Isaac Newton’s Newton, Sir Isaac;reflecting telescope invention of the reflecting telescope corrected these aberrations, and astronomers of the eighteenth and nineteenth centuries developed larger and larger reflectors. In 1781, the German-English astronomer William Herschel used his large reflecting telescope to discover the planet Uranus. In the nineteenth century, the Irish astronomer William Parsons built a seventy-two-inch reflecting telescope with which he was able to discern the spiral shapes of nebular objects. Seventy-five years later, the American astronomer Edwin Hubble, using the hundred-inch Mount Wilson telescope in the mountains of Southern California, showed that these nebular objects actually were systems of stars far beyond our Milky Way galaxy. Named in his honor, the Hubble Space Telescope has continued the long and glorious history of this instrument in revealing the great mysteries of the universe.

• Asimov, Isaac. Eyes on the Universe: A History of the Telescope. Boston: Houghton Mifflin, 1975. A chronicle of astronomy by a skillful and knowledgeable popularizer that centers on the evolution of increasingly sophisticated telescopes.
• King, Henry C. The History of the Telescope. New York: Dover, 1979. This reprint of a classic work originally published in 1955 has been called by Owen Gingerich, a distinguished historian of astronomy, “the last word” on this topic. This extensively illustrated book contains much information unavailable elsewhere, along with many references to primary sources and a detailed index.
• Moore, Patrick. Eyes on the University: The Story of the Telescope. New York: Springer-Verlag, 1997. Written to commemorate the fortieth anniversary of the British television series “The Sky at Night,” this illustrated account of the telescope’s history is intended for general readers and amateur astronomers.
• North, John. The Norton History of Astronomy and Cosmology. New York: Norton, 1995. North, a professor in the history of the exact sciences, discusses the telescope as part of the evolution of astronomy. Includes an index and a thirty-four page bibliographical essay.

Gian Domenico Cassini; Galileo; Robert Hooke; Christiaan Huygens; Johannes Kepler; Hans Lippershey; Maurice of Nassau; Sir Isaac Newton. Telescope;invention of