The origins of the telescope date back to an accumulation of knowledge and visual observations that spanned centuries, before Galileo Galilei took his famous step in the summer of 1609. The ancient Arabs were credited with laying the foundation.
On August 25th of that year, Galileo presented a new optical device to the Grand Council and the Doge of Venice. It consisted of two simple lenses and magnified objects only three times. What was truly astonishing, however, was that Galileo had never seen a complete telescope before. Instead, he relied on his profound understanding of the laws of optics to create his own instrument, significantly improving the initial design and adding a level of precision unavailable in previous models. The Italian astronomer recognized the practical value of his invention from the outset, asserting that it could be used to observe ships approaching port two hours before their arrival, a fact that impressed both the public and those in positions of power.
This achievement did not come out of nowhere, as the first seeds of the idea of optical magnification had appeared long before. In the memoirs of Leonardo da Vinci, specifically in 1509, we find drawings of a simple lens alongside the phrase: “Make glasses to see the full moon,” which indicates that the concept of observing distant objects was present in the human mind, even if it remained confined to theories and was not translated into a practical device.
In Europe, numerous workshops witnessed repeated attempts, both intentional and accidental, to place two lenses in succession, along with observations of the magnifying effect. Stories abound of children of opticians who, while playing with their fathers' lenses, discovered that a specific distance between the convex and concave lenses was sufficient to magnify distant objects, paving the way for later, more systematic experiments.
At the beginning of the seventeenth century, specifically in 1608, Johannes Lippershey from the Dutch city of Middelburg submitted a device capable of magnifying distant objects and applied for a patent for it, but his application was rejected due to the existence of similar devices previously made by Zacharias Jansen and Jacob Meteus.
These early Dutch telescopes were designed as practical tools for soldiers and sailors, helping them observe ships and fortifications from a distance, before evolving into astronomical instruments. Centuries earlier, since the 13th century, Italy had established a long tradition of crafting eyeglass lenses, beginning with convex lenses for farsightedness and then concave lenses for nearsightedness. This contributed to the mastery of glass grinding and polishing techniques, essential skills for creating precise telescopes. Due to the poor quality of ready-made eyeglass lenses at the time, Galileo was forced to make his own lenses, drawing on this accumulated expertise.
The scientific legacy of Arab-Islamic civilization cannot be overlooked in this context, as the achievements of its scholars in optics, astronomy, and instrument making contributed to laying the theoretical and practical foundations that made the telescope possible. Among the most prominent of these scholars was Ibn al-Haytham in the eleventh century CE, who wrote pioneering works on the analysis of light and vision, and described the properties of lenses and mirrors, which became an important reference for those who came after him, including Galileo himself.
In January 1610, Galileo returned to developing his telescope, increasing its magnification to thirty-three times, which opened up unprecedented cosmic horizons for him. With this improved instrument, he discovered four moons orbiting Jupiter, later known as the Galilean moons, and observed craters and mountains on the Moon's surface, refuting the prevailing belief in its smooth surface. His observations also revealed the phases of Venus, he witnessed sunspots, and he realized that the Milky Way was not a cloud of light, but a vast collection of individual stars. All these findings revolutionized humanity's understanding of the universe and confirmed that the telescope was no longer merely a military or naval tool, but a window onto new worlds, making Galileo a symbol of experimental science and cementing the telescope's place as one of the most important inventions in human history.
