While Galileo was a prolific inventor, it’s a misconception to credit him with the invention of the telescope. Historical records suggest that the telescope might have been the brainchild of a German-Dutch spectacle maker, Hans Lippershey, who lived in a small town in The Netherlands. It was Lippershey who, in October 1608, lodged the earliest known patent application for a refracting telescope yielding 3x or 4x magnification. He also attempted to sell the Dutch government a very early version of a pair of binoculars consisting of two of the devices side-by-side.
Another myth says that he stole the idea from Zacharias Jansen, another lensmaker who lived in the same town. Whatever really happened, the fact remained that Hans Lippershey played an important role in the creation of the telescope, and he is credited with its invention due to his filing for a patent for it.
Despite Hans Lippershey’s pioneering role in the development of the refracting telescope, the winds of fortune didn’t always blow favorably for him. When he submitted his patent application for the groundbreaking device in 1608, he might have envisioned it as a surefire path to securing his intellectual rights and reaping the rewards of his invention. However, the patent request was denied by the Dutch States General.
The precise reasons for the denial of Lipppershey’s patent remain a topic of historical debate. Some suggest that the decision was influenced by the fact that there were multiple claimants around the same time who asserted to have invented the telescope. We know today of possible accounts of telescopes made as early as the late 1500s—a few decades prior to Galileo and Lippershey. Others believe that the concept of magnification was not novel enough to warrant a patent at the time, as rudimentary magnifying glasses had been in use for centuries and the patent authorities did not quite understand the difference between Lippershey’s new device and a simple convex lens. The weak magnification of the telescope Lippershey demonstrated was also unlikely to have been seen as impressive, especially given the lack of clarity in the resulting image.
While Galileo did not invent the telescope, his enhancements to it and his revolutionary astronomical observations using the device are what carved his indelible mark in the annals of science. The “Galilean telescope,” as it’s now known, became a symbol of a man who dared to look further into the cosmos than anyone before him.
In 1611, Galileo’s instrument received the name “telescope” for the first time, created from the Greek words “tele”, meaning “far”, and “skopein”, meaning “to look or see”. Later that year, Johannes Kepler published a theory demonstrating the increased effectivity of a telescope that used two convex lenses. Kepler’s telescope design eventually led to the creation of the first true refractor telescopes.
Why wasn’t the telescope invented sooner?
Short answer: it probably was, albeit in a completely impractical form, written by Leonard and/or Thomas Digges in the mid-1500s, but first a bit of backstory.
The understanding and craft of lenses were no strangers to ancient civilizations. The Greeks and Romans studied mathematical theories of optics and were aware of the properties of concave surfaces to focus light, such as the apocryphal (but sadly disproven) story that Archimedes used bronze concave mirrors to set an attacking Roman navy on fire.
Fast forward to the Islamic Golden Age, and we find the Arab Egyptian physician Alhazen, a 10th-century polymath who was at the forefront of optics research. His seminal work, the “Book of Optics,” profoundly influenced the trajectory of optical studies, and his insights were pivotal for the generations that followed. Alhazen pioneered the study of the scientific method as well as observations of sunspots with a camera obscura. If anyone could’ve come up with the telescope in the medieval era, it was probably Alhazen, who clearly had sufficient knowledge and interest in both astronomy and optics, as well as access to a sufficient industrial base, for such an idea to come about. Unfortunately, he never did.
Despite such early forays into optics, Europe remained relatively untouched by these advancements until the 13th century. Around this period, the European continent began to embrace the wonders of basic magnifying lenses, marking a pivotal turning point in the realm of visual aids. The translated works of Alhazen, as well as those of other European and Islamic scholars, were pivotal to these innovations.
By the dawn of the 14th century, cities that were flourishing centers of trade and culture, like Venice and Florence, witnessed the introduction of eyeglasses. This wasn’t merely an introduction; it sparked a renaissance in lens-making. Artisans honed their skills, refining techniques to polish and shape lenses with unprecedented precision.
Given the rapid advancements in lens crafting, it might seem perplexing that the development of the telescope, a device that essentially hinged on lens technology, lingered in obscurity for a while. The elements were present, the knowledge was accessible, and yet the conceptual leap to create the telescope was seemingly elusive. Many scientists throughout the late medieval period seemed to be aware of the magnifying properties of lenses, but little seems to have come of it.
The ancient Romans had glass good enough that they could’ve made objective lenses for small refracting telescopes, and enough of an industrial base that silvered glass mirrors or metal speculum mirrors for reflecting telescopes would’ve been possible too. While manufacturing a small concave or convex lens for an eyepiece might have been difficult, a ball lens could’ve been cast out of a glass bead (the famed astronomer William Herschel used such eyepieces for many of his observations). Similarly, by the time of the Renaissance, glass technology and an understanding of optics in Italy and other European hubs of innovation were sufficient to have built a telescope by the time Columbus set sail in 1492, at the latest.
Was the telescope actually invented in England?
Interestingly enough, we do have some evidence that telescopes may have even been invented well before Lippershey and Galileo, with the strongest candidate being Leonard and Thomas Digges sometime in the latter half of the 1500s.
Leonard Digges, born in 1515, was not just an English mathematician but also the brain behind the invention of the theodolite, a precision instrument used in surveying and building. Leonard’s impact on the world of scientific understanding didn’t stop at his own contributions; it was expanded and propagated by his son, Thomas Digges. Thomas not only amplified his father’s work but was also instrumental in popularizing Copernicus’s groundbreaking book, “De revolutionibus orbium coelestium.”
In a publication titled “Pantometria” in 1570, Thomas included notes that alluded to Leonard’s experiments with a device he termed a “proportional Glass.” This intriguing instrument was described as having the capability to magnify distant objects, allowing the viewer to see far-off entities with clarity. Historians and astronomers have postulated that this could very well be an early description of a telescope crafted sometime between 1540 and 1559.
Further insights into the Digges’ telescopic ventures come from a detailed letter penned by William Bourne in 1580 to Queen Elizabeth’s trusted advisor, Lord Burghley. In the letter, Bourne meticulously outlined the foundational principles of optics. He delved into the art of grinding a “perspective glass”, or objective lens. Bourne introduced the idea of merging this lens with a concave mirror to create the aforementioned “proportional glass.” Recognizing its potential military significance, he emphasized its value while also modestly deflecting from his own expertise. Instead, he highlighted John Dee and Thomas Digges as the true maestros in the practical applications and creation of such devices. It is almost certain that either Leonard or Thomas had succeeded in developing a telescope with this design by this point.
The telescope as described by Bourne (often referred to as Digges-Bourne) would’ve used a convex objective lens like Galileo’s or Lippershey’s telescopes, but rather than an eyepiece, it had a convex mirror shortly before the image reached focus, serving as a sort of magnifying glass roughly equivalent to the function of an eyepiece. If this sounds bizarre, well, it is. The Digges telescope would’ve formed a sort of “floating” image some distance from the mirror. You had to look through it backwards, which already made things confusing. Furthermore, the resulting image was likely very dim (suitable metal mirrors at the time were no more than 50–60% reflective) and not nearly as sharp as a pure refracting telescope, and thus it was impractical to actually use. There is no record that this crude telescope was pointed towards the heavens, but it certainly would’ve been powerful enough to resolve the craters on our Moon, the moons of Jupiter, and the phases of Venus. Functional replicas have been built in modern times that confirm the viability of the design. (1) (2)