The ability for convex and concave transparent objects to enlarge or reduce had been known since Antiquity and by the end of the thirteenth century; quality glass was relatively inexpensive, particularly in Italy. At the same time, techniques for grinding and polishing had reached a high state of relative precision in Venice. So, handheld magnifying glasses became relatively common. During the fourteenth century, the craftsmen of Venice began producing small double-sided convex glass disks that could be mounted and worn in a frame- the first reading glasses. By the middle of the fifteenth century the Italians were also producing spectacles that corrected for nearsightedness. Therefore, around 1450 the ingredients to produce the first telescope were in place but it would be another 150 years before children would trigger its invention and change everything.
Spectacles became popular throughout Europe during the two hundred years following 1300 and could be purchased from a spectacle maker’s shop. Generally, a suitable pair was selected by trying on different glasses until one provided the best vision improvement. Interestingly, peering through a lens that corrects for nearsightedness, held near your eye, then through a lens that corrects for farsightedness, held farther away, will magnify objects in the distance. Why no one stumbled upon this until the early 17th century remains a mystery given the wide availability of these lenses. Regardless, the first telescopic view may have occurred not through a pair of lenses but through a lens and mirror produced by two Englishmen, Leonard and Thomas Digges, in the 1570’s. Unfortunately, their experimental instrument never reached maturity.
Finally, in late September 1608, Hans Lipperhey, a German-born spectacle maker who had settled in the Netherlands, requested a patent on a new optical instrument. It featured a convex and concave lens mounted on a tube about one foot in length that could make far away objects seem three or four times closer. It is said he got the idea when his children, who were playing in his shop, looked through two lenses and could see the weathervane on a distant church as if it were much closer. During the review of his application, he was asked to make an improvement so that the instrument could be used with both eyes; therefore Lipperhey also produced several binocular telescopes as a result of his patent request. Unfortunately, the news of his invention did not remain a secret during the patent review, undoubtedly due to the bureaucracy involved with granting approvals. For example, his application was shared with a high-ranking official of the Vatican who immediately dispatched a message to Rome and thus news of his invention started to spread across Europe as fast as coaches could carry it. Ironically, Lipperhey’s patent was denied on the basis that his invention could not remain secret and was too easy to copy.
It is noteworthy that two other spectacle makers also claimed to be the telescope’s inventor. Jacob Metius presented his patent petition shortly after Lipperhey’s was rejected and Sacharias Janssen made a similar assertion several decades later. While Hans Lipperhey was never officially recognized as the inventor of the telescope, and thus did not reap what would have been a considerable fortune, he is nonetheless credited with its discovery because his was the first written submission for a patent of the telescope’s design.
Within six months of Lipperhey’s patent attempt, spyglasses, as they were called, could be purchased in Paris and four months after that they could be bought in Italy, too. The telescope so thrilled people that it became one of Europe’s most popular toys. A mathematics professor at the University of Padua, Italy, on the lookout for any opportunity to offset the costs of supporting his family, learned of the telescope and set about to build his own but make it better. Unlike the craftsmen who built the first telescopes, Professor Galileo leveraged his mathematical background to improve the quality of his lenses.
He constructed his first telescope during the summer of 1609, presented an eight-powered instrument to the Senate of Venice in August (for which he was handsomely rewarded), and then turned a twenty-powered instrument to the heavens early in the fall of the same year. He observed the Moon, discovered the four largest satellites of Jupiter, and found that the Milky Way was made of individual stars- all this was with the latter telescope. In March 1610, he published his discoveries in The Starry Messenger and stood the universe, as humankind understood it, on it’s head.
At first, no one could verify all of Galileo’s discoveries- telescopes other than his were optically inferior. For example, independent verification of Jupiter’s moons waited six months after Galileo’s publication before others could obtain instruments of sufficient quality. The phases of Venus would not be corroborated until the first half of 1611 but by this time, Galileo’s lead in telescope making had ended. His next discovery- sunspots- was made my several observers independent of each other.
Interestingly, just as Galileo did not invent the telescope, neither was he the first to observe the sky with the new instrument. That distinction goes to a little known Englishman named Thomas Hariot who observed the Moon with a six-powered spyglass early in August 1609. His telescopic drawing of the Moon, during early August 1609, is the first on record and preceded Galileo’s lunar studies by several months. Hariot’s observation of sunspots during December 1610 was also made prior to Galileo’s.
Other than A Brief and True Report, Hariot did not publish his work whereas Galileo did. Both the distribution of his words and the controversy that turned him into a prisoner gave Galileo the stature that he occupies to this day. Conversely, Hariot left a large number of manuscripts on various scientific subjects that have, over the past three centuries, only slowly surfaced. As a result, Hariot remains somewhat unknown.
The object that appears in the picture accompanying this article would have been totally invisible through any of the one hundred telescopes produced by Galileo during his lifetime.
First, his telescopes suffered from various optical flaws. For example, Galileo’s instruments had a narrow view- at twenty times magnification only a quarter of the moon was visible. They also had color aberrations- bright objects were surrounded by false halos or fringes of distracting hues. Their focus was not flat- it was best at the center of the image and grew fuzzy towards the edge of the field of view. Telescopes are a reflection of the technology at the time they are produced and Galileo’s lenses were also filled with air bubbles and tinted green due to the iron content of the glass from which they were made.
Second, his telescopes were small. They had an aperture- the diameter of the front lens- of between one half and one inch. That severely restricted the amount of light entering into the observer’s pupil. The primary purpose of an astronomical telescope is to collect light. For example, the telescope used to produce the picture featured with this article had a light gathering surface that was ten inches in diameter. That means it collects over 1,500 times more light than the eyes of a normal 40-year-old person- stars appear 1,500 times brighter when viewing the sky through this size of telescope. Conversely, Galileo’s largest telescope collected only 15 times as much light. Of course, the comparison is not completely fair. We are talking about 21st Century technology versus renaissance period artifacts built almost 400 years ago.
The picture featured here is of a planetary nebula in the northern constellation of Cygnus, the Swan. It was designated as number 7048 in J.L.E.Dryer’s New General Catalog which also described it as “pretty faint, pretty large, diffused, and irregularly round.” Long exposure photographs, of course, bring out its true appearance. NGC 7048 is located about 6,200 light years from Earth.
This beautiful, detailed image was produced by Stefan Heutz from his private observatory. It was taken through a ten-inch telescope and a 1.3 mega-pixel astronomical camera. Stefan exposed this picture for about three and a quarter hours.
Written by R. Jay GaBany