Telescopes are remarkably simple in concept: Just look in one end, and marvel at the magnified stars and planets on the other end, right?! They truly are an impressive feat of technology, and today there are many different kinds of telescopes, some dizzyingly impressive.
Have you ever wondered how telescopes came about? Who invented the telescope, and why? What were early telescopes like? And what are today’s telescopes capable of doing?
The story of the telescope is a relatively long one—spanning multiple centuries and countless refinements in design. Like any good story, it’s filled with a cast of quirky characters, mishaps and setbacks, and astounding feats of ingenuity.
1) Telescopes are not the oldest astronomical instruments
Even if you have absolutely no access to a telescope, you can still learn more about the stars and planets with just your eyes. Plus, plenty of other astronomical devices like the astrolabe preceded the telescope in history.
Even before people recorded their histories in writing, they have looked up into the night sky and imagined various stories playing themselves out in the heavens.
Just as people have forever wondered about the Milky Way, the Northern Lights, and the constellations, so have they sought out ways to see them more clearly, to map them, to record their movements. Astronomy no doubt began its long life as a human art and science with people sitting down after a long day and simply looking up.
As such, the first human astronomical instrument was the timeless eyeball (patent pending). In a world without light pollution and few distractions, the night sky is a nearly endless source of both entertainment and stories, as I have learned myself while out backpacking in the wilderness.
For a very long time, people could not make any sort of precise machine with which to observe or measure the stars. And to be totally honest, there was no need to do so among hunter gatherers or early agriculturalists.
But as civilizations began to grow in what we now call Egypt, Mesopotamia, the Balkans, and elsewhere, people began to form more complex stories about their cosmos. And with those stories people desired greater knowledge.
It is speculated, though to this day not known certainly, that marvels like Stonehenge in England were ways to measure time by the sun, the moon, and the stars.
And once people refined their metalworking techniques, they began to use that talent for their fascination with the skies above them.
Numerous astronomical tools and technologies proliferated before the invention of the telescope.
An incredibly old sundial still remains in the Valley of the Kings, where many Egyptian pharaohs were buried, including the famous King Tutankhamen himself. Early astrolabes date from about two thousand years ago, but as is often the case with history, exact dates are impossible to know.
Actual telescopes came along relatively late in the astronomy craze. Most famously, the Italian Galileo Galilei used a telescope to make observations of the heavens. These observations led him to the then radical conclusion that the Earth was not the center of the universe, as was commonly believed at the time.
This conclusion brought him into direct conflict with the Roman Catholic Church, which was then struggling against the Protestant Reformation and looming religious war in Europe. It was an odd twist of history that the Church attacked Galileo, as the Church was itself the institution in Europe that had preserved so much scientific and academic knowledge from the lost Roman world.
The other main source for astronomical manuscripts in Europe was the Muslim world, where scientists and theologians had diligently copied and translated volumes of writers like Aristotle and Plato.
And so by the time telescopes entered the intellectual world, astronomy was already an ancient practice, and people were on the cusp of beginning what in hindsight earned the name “the Scientific Revolution.”
2) Telescopes aren’t just for astronomical observation
In the early days, they were commonly used for terrestrial observation, in particular for naval warfare.
Initially developed in the first decade of the 1600s in the Netherlands, many early telescopes were never meant to be pointed at the sky above.
In 1608, the Dutch government considered and ultimately rejected issuing a patent for an optical tube which would allow for “seeing faraway things as if nearby.” This may have been the first telescope, though the exact inventor remains in debate to this day, though Hans Lippershey often receives the credit.
At any rate, this strange invention was not only useful for astronomical observations, but also for naval warfare.
In the age of sail, men sat atop masts day and night, constantly on the lookout for threats, whether enemy warships or simply bad weather. A telescope would allow a person to see these threats sooner, though of course the horizon would still be a hard stop on human visibility.
Possibly the most famous military use of a telescope actually comes from a story of the misuse of one of these devices.
In 1801, as the War of the French Revolution raged not only across Europe but really across the entire world, a British Navy officer named Horatio Nelson was in the Baltic Sea. He led part of a battle group tasked with destroying or at least containing the Danish fleet, as Denmark at the time was allied with France.
When he sighted the Danish Navy at anchor in Copenhagen itself, Denmark’s capital, he wished to attack even though those ships were protected by artillery pieces in shore batteries. As Nelson lined his ships for the assault, his commander ordered him to retreat by using semaphore, a system of flags which allowed for long-distance communication between ships.
When his subordinates informed him that the commander, Admiral Parker, was signaling him, Nelson raised the telescope to his damaged eye and reported that he saw no such command. This episode is credited with originating the phrase “turn a blind eye”!
Nelson continued the attack and obliterated the Danish Navy at anchor. He later died at the decisive Battle of Trafalgar in 1805, in which he led a two-pronged assault on a much larger Franco-Spanish fleet.
In any event, seafarers and astronomers alike had reason to celebrate the 17th-century emergence of the telescope!
3) Galileo helped make the telescope famous
Although he was not the inventor, he encountered the telescope in the 1600s and rapidly produced new and improved telescopes of his own, which he showed to his wealthy and influential patrons.
As noted above, Italian professor Galileo Galilei is one of the most famous people ever to use a telescope. He was working at the University of Padua in the early 1600s when he became acquainted with what was then a newfangled invention.
Galileo began to come up with his own designs, building multiple telescopes for himself and his powerful patrons, each telescope more powerful than the last.
His first design was a three-power telescope (meaning that it had 3x magnification). It wasn’t the most impressive thing to look at, just a simple tube with a couple of lenses in it. He continued refining his designs, eventually crafting a telescope with around 30x magnification.
By modern standards, these early telescopes weren’t particularly powerful. Nevertheless, what Galileo accomplished with them had a massive impact on physics and astronomy.
What did Galileo see through his telescopes? He looked at the sun and noticed that there were dark spots on it (now known as “sunspots”). Furthermore, he observed that these spots were in motion, indicating that the sun was rotating on an axis—a new piece of information.
He observed the moon and saw that it had a rough surface with many craters and mountains; it wasn’t smooth as people had previously believed.
He saw Jupiter through his telescope as well as four little points of light that circled around the planet—the four brightest moons of Jupiter.
Galileo made numerous other observations through his simple telescopes, greatly expanding our knowledge of astronomy, physics, and the entire universe. He supported the then-controversial model of heliocentrism, a view of the solar system with the sun at the center, not the earth.
His new ideas challenged the ancient Aristotelian view of the universe and also got him into trouble with the Church. But even while under house arrest, Galileo kept writing and publishing, earning his title as “the father of observational astronomy.”
4) Even a low-quality modern telescope far exceeds anything used by Galileo
While his telescopes were certainly impressive for his time, modern designs have continued to improve, making it possible for millions of people—not just the elite—to own a quality telescope.
Galileo’s telescopes, and those used by militaries of the era, were simple refracting telescopes.
The eyepiece lens was concave, whereas the objective lens, facing the target of observation, was convex. This design was very simple and easy to make, especially given limited lens-making methods of the Renaissance.
However, this design had major limits. First, Galileo’s first attempt was only a three-power device, whereas his final iteration was around thirty power.
For reference, a common modern hunting scope for a rifle can easily have between nine and twelve power, and affordable scopes over twenty power are easy to come by. But magnification is far from the best standard by which to measure optics; the winner there is optical clarity.
Early refractor telescopes didn’t score too well on clarity either though. Telescopes of the time period produced blurred images with color distortions on the edges of objects. Even worse, the field of view was abysmal.
Imagine trying to observe the solar system through the viewing field of a drinking straw. Or even just try to imagine viewing your own bedroom that way. Early astronomers were incredibly limited by their own equipment, though to be fair, any telescope was a step up from nothing at all.
Today, even a poorly made telescope should have vastly superior lens quality when compared to those old telescopes. Also, their magnification will be better, though that matters far less than optical clarity. Even better, modern optics of most sorts can be quite affordable, which they were certainly not for Galileo.
5) When it comes to buying a home telescope, aperture is key
Aperture determines how effective your telescope is at collecting light, and it’s a much more important feature than, say, magnification, flashy extras, or aesthetics.
What is aperture, and why should you care about it?
The aperture is simply the diameter of the main objective piece through which light enters the telescope body. Your telescope’s aperture is the most important piece of the entire thing. Without it, you only have an expensive tube that does nothing.
Depending on the exact type of telescope you may have, the aperture can actually be either a lens or a mirror, whatever light hits first. On Galileo’s primitive refractor telescope it was a lens. On a reflector telescope, it is a mirror.
A bigger aperture means more light collection. A larger aperture will increase cost, simply because the precision machining required to make a good quality lens is costly.
A good, high-quality, and large aperture will allow for excellent light transmission. This is especially important if you plan on viewing the sky from a place with some degree of light pollution.
If your idea of the outdoors is Central Park, then you really will need a large aperture telescope, or else the lights of the city will simply drown out everything else. In contrast to that, a telescope with a large aperture can even let you see distant galaxies from an urban area.
When you’re buying a telescope, focus on lens quality and aperture size. Magnification is not the key factor at all.
In some cases optics will have high magnification but poor optical quality, leading to absolutely awful images and low clarity. Also, looking through a telescope with poor optical clarity can cause headaches and sore eyes.
So once you’ve done your research for buying that first telescope, make sure whatever you end up buying has quality optics. As the old saying goes, buy once, cry once. A badly made telescope can hurt your interest in astronomy if it’s bothersome to look through, so buy quality.
6) The first working space telescope was launched in 1968
NASA sent up four Orbiting Astronomical Observatories in the 1960s and 70s, two of which carried out successful missions. These early space telescopes were precursors to the famous Hubble Space Telescope.
First off, what is a space telescope? As the name suggests, it’s a telescope in outer space, and its purpose is to observe faraway astronomical bodies and objects: Planets, moons, asteroids, galaxies, nebulae, star clusters, and more.
Space telescopes are not the same as other satellites that encircle Earth and perform meteorological observations or espionage.
So why do we need telescopes up in space anyway? Can’t we see all those things from down here on Planet Earth? Well yes, but there are definitely advantages to space telescopes.
They generally can get clearer images of things, and they avoid the problem of light pollution on the ground. Plus, they are also able to pick up on infrared and ultraviolet waves as they pass through space. Ground telescopes can’t do this, since Earth’s atmosphere absorbs and blocks these waves.
On the other hand, space telescopes are pretty expensive! And since they’re in outer space, they’re awfully hard to repair if something goes wrong. Many space telescopes can’t even be repaired while they’re out in space. Luckily, the Hubble Space Telescope at least is designed so that astronauts can fix it in space.
Where did these space telescopes come from? Back in the 1940s, physicist and astronomer Lyman Spitzer had the idea of placing telescopes in space to overcome the limitations of ground-based telescopes.
During the 1960s, this vision became a reality with NASA’s Orbiting Astronomical Observatory (OAO) satellites. Four of these observatories were launched, though the first launch in 1966 ended in failure.
Undaunted, NASA sent up OAO-2 in 1968. It carried over 11 ultraviolet telescopes and successfully carried out its mission for several years, making new discoveries about comets and novae.
A third space telescope, OAO-B, unfortunately failed to enter orbit, but the fourth and final OAO, sponsored by NASA and the UK’s Science Research Council, performed extremely well. This OAO was also known as Copernicus, in honor of the 500th anniversary of the famous Renaissance astronomer’s birth.
The success of (some of!) these early space telescopes paved the way for the creation of the famous Hubble Space Telescope, an enormous piece of equipment that has been orbiting Earth and capturing fantastic images since 1990.
7) A new space telescope—the James Webb Space Telescope (JWST)—will be launched soon!
Weighing in at 6500 kilograms (14,300 pounds), it will start observing extremely old and distant objects when it (hopefully!) launches in 2021.
The James Webb Space Telescope is poised to make some major breakthroughs in astronomy. Have you ever wondered how stars and planets get formed? Or even how the first galaxies came into being? The JWST may shed some light on these exciting questions.
Created by NASA, the Canadian Space Agency, and the European Space Agency, this space telescope was supposed to launch in summer 2018, but its debut has been pushed back until 2021.
A little delay isn’t exactly surprising given the complexity of this incredible machine. The JWST will be the largest telescope ever sent into space. Its main mirror, comprising 18 hexagonal segments, boasts a 6.5-meter diameter, substantially larger than the Hubble’s (2.4-meter diameter).
The JWST also requires protection from the sun and other heat sources. It must be kept cold to function at its best. It therefore has an incredibly powerful sunshield, which is basically SPF 1 million.
All in all, there are over 1200 people hard at work on this space telescope, perfecting every element of its design.
The JWST will observe objects in the mid-infrared range (as opposed to, say, visible or ultraviolet spectra). What this essentially means is that the JWST will be able to detect things that are older and even further away.
In some ways, the JWST isn’t just a telescope; it’s also a time machine, looking 13.5 billion years into the past to learn more about the young universe and its earliest galaxies.
Want to watch as a star is born? Perhaps the JWST can make it happen.