The telescope has undergone an enormous transformation since it was first developed in the 17th Century. Some of the greatest minds from Galileo Galilei to Sir Isaac Newton to the great Edwin Hubble would all contribute, over time, to the development of some of the most advanced scientific pieces of equipment ever devised by man.
In the following article, we will journey through time and explore 15 of the most significant telescopes, and their inventors where applicable, in history ranging from the first recorded telescope to space-based telescopes observing everything from visible light to gamma rays.
The following list is in chronological order but is not exhaustive.
1. The telescope was first patented in 1608
Dutch eyeglass maker Hans Lippershey (or Lipperhey) is widely credited as the first person to patent a telescope in 1608. His device, called a kijker ("looker"), was, according to Hans, able to magnify an image up to three times.
It consisted of a concave eyepiece that was aligned with another convex objective lens. According to legend, he conceived of the idea when seeing two children holding up two lenses that appeared to make a distant weather vane appear closer.
Despite his patent, some contemporaries claimed he stole their idea. One notable example includes another glassmaker from the same town called Zacharias Jansen.
Many historians fully recognize Lippershey as the inventor of the first telescope; however, it is due to his actual patent application. It does appear that both men independently created their own designs with Jansen being credited with inventing the compound microscope.
This, however, was not the end of the story. Jacob Metius also laid claim to the invention of the telescope shortly after Lippershey. When he also applied for a patent both applications were rejected due to the counterclaims and the official's opinion that it was easy to reproduce.
Both men received a reward with Metius receiving a nominal sum, and Lippershey was awarded a significant commission to make copies of his telescope. His telescopes would later be supplied to high society around Europe, including Henry IV of France.
It was Hans' telescope that would later catch the eye of Jacques Bovedere of Paris. He reported the invention to none other than Galileo Galilei who promptly began to build his own.
2. Galileo used his telescope to peer into the cosmos
Galileo heard about Hans Lippershey's ingenious device via his French associate Jacques Bovedere in 1609. He immediately set about designing and building his own design without even seeing Han's device.
He was able to make significant improvements on the performance of his telescope reaching magnifications of around 20 times. Pleased with his creation he subsequently presented it to the Venetian Senate who rewarded him as a lecturer at the University of Padua for life.
As impressive as this was he went further, as history attests. Galileo would be the first recorded person to point his telescope skyward. With his telescope, he was able to make out the cratered surfaces of the moon, drew the moon's phases in detail, and even described the Milky Way.
His observations also led him to discover the rings of Saturn, sunspots and Jupiter's moons. Galileo would quickly become convinced that Copernicus's Heliocentric model was absolutely correct - a position that would ultimately see him put under house arrest by the Catholic Inquisition until his death in 1642.
3. The Keplerian telescope was devised in 1611
After the groundbreaking work of Hans Lippershey and Galileo Galilei other scientists around Europe began to design and build their own telescopes. Chief amongst the early pioneers was the one and only Johannes Kepler.
Kepler made detailed studies of telescopic optics and devised his own apparatus with two convex lenses - the famous Keplerian Telescope. He built it in 1611 and it greatly improved the device's magnification but rendered the observed image upside down.
Apart from his significant contributions to astronomy, he was instrumental in the field of optics in general. His groundbreaking manuscript Astronomia Pars Optica would earn him the title of the 'Founder of Modern Optics'.
This book contained his observations and rationalization about many aspects of optics including the use of pinhole cameras to take pictures, explanations of the refraction in the eye and his understanding of the depth perception.
A later work, Dioptrice made him the first person in history to describe real, virtual, upright and inverted images and the concept of magnification. He would also become the first person to explain how a telescope actually works.
Kepler also discovered the properties of total internal reflection.
4. Christian Huygens uses his DIY telescope to find Titan
Dutch astronomer Christian Huygens, inspired by the earlier works of Galileo, was inspired to build the most powerful telescope of the day in 1655. His enormous apparatus (for the time) was built to make detailed studies of the planets and solar system.
Huygens's greatest contributions to the development of telescopes were his invention of the Huygens ocular and the aerial, or tubeless, telescope. He would also show the great utility of a micrometer.
Christian also made great improvements to the grinding of lenses beginning in 1654. After some consultation with well-known opticians, he and his brother acquired some grinding plates and other equipment needed to build a telescope.
After some trial and error, a 12 foot (3.7 meters) telescope was ready for use. He would quickly use it, to his great satisfaction, to make detailed observations of Saturn.
Using his telescope, Huygens was able to observe a bright moon that orbited Saturn which he dubbed 'Saturni Luna'. This name stuck until John Herschel renamed it Titan in 1847. Christian also studied Saturn itself in great detail using his telescope and was the first to document the true shape of the planet's rings in 1659 - they had previously been referred to as the 'ears' of Saturn.
5. Isaac Newton built the first reflecting telescope
Sir Isaac Newton would later build on the work of his forebears, notably Kepler, to reason that perhaps telescopes should use a series of mirrors rather than lenses. He believed, amongst other things, this setup would solve the chromatic aberration issues that plagued refracting telescopes.
Newton believed that this issue could never actually be cured in refracting telescopes and resolved himself to find a new solution.
Following through on his thoughts the first reflecting telescope, the Newtonian Telescope (Reflector) was built in 1668. Newton's breakthrough was to use a large concave primary mirror focusing light (objective) onto a smaller flat diagonal mirror that projected an image into an eyepiece on the side of the telescope.
Contrary to popular belief, however, Newton was not the first to devise of the idea of a reflecting telescope. Galileo Galilei and Giovanni Francesco Sagredo had discussed the possibility after the invention of the refracting telescope.
Other scientists of the time like Niccolò Zucchi, may have conducted similar experiments in 1616. It is also possible that Newton read James Gregory's 1663 book Optica Promotathat had a description of reflecting microscope concepts using parabolic mirrors.
Newton's telescope would prove to have a number of advantages over existing models of the time.
- No chromatic aberration
- Cheaper to build
- Construction and assembly was a lot simpler
- Wider field of view due to short focal view
- The design was much shorter and more compact than its predecessors. Making it more portable.
5. Chester Hall solves the color distortion issue with refracting telescopes
For the next 60 years or so, minor improvements were made to the technology by the likes of Laurent Cassegrain (who introduced hyperbolic and parabolic mirrors) and John Hadley (who improved Newton's model) the next big leap came in 1729.
An Englishman, Chester Moore Hall, greatly reduced the chromatic aberration of refracting telescopes when he introduced a new form of a lens. This lens consisted of two types of glass, the crown, and flint, that were cemented together.
With this development, Hall proved that Isaac Newton was in error with his proposition that color distortion could not be solved using refracting rather than reflecting telescopes.
He discovered his solution by studying the human eye. This led him to the belief that achromatic lenses must be possible somehow.
He experimented with many kinds of glass until he found the perfect combination of crown and flint glass that met his specific requirements. In 1733, he built several telescopes with apertures of 2.5 inches (6.5 cm) and focal lengths of 20 inches (50 cm).
6. The first gigantic telescope is built
In 1789, the first giant reflector telescope was built in the UK. William Herschel oversaw the construction of a 12-meter long Newtonian based reflector telescope.
This enormous telescope was the largest in its day and would have been a real sight to see. As impressive as this must have been, it was far from perfect.
Herschel solved an issue with the poor reflective quality of speculum metal often used in Newtonian Telescopes. He did this by simply omitting the diagonal mirror completely and tilted the primary mirror to allow the user to directly view it.
This would come to be known as the Herschelian telescope.
Herschels huge telescope had a number of issues that would lead him to prefer to use a smaller 6-meter long telescope for astronomical observations.
Using his telescopes, Herschel was able to discover some moons around the gas giants, notably Titania and Oberon of Uranus and Uranus itself. William, using his bigger telescope, was able to find the sixth and seventh of Saturn's moons - Enceladus and Mimas.
7. 1800's: Rise of the giant telescopes
Speculum tends to be very hard to cast and shape and also quickly tarnished in humid climates - just like Ireland. However, after three attempts the Earl and his team were able to successfully make two mirrors for their new telescope. The second mirror was a spare for use when the first mirror needed maintenance works every six months or so.
Today, we can routinely make large mirrors, some in excess of 9 meters. In the 1800s, however, it was a much more challenging endeavor. Today's mirrors tend to be made by coating glass in reflective metal, back then mirrors were cast from a heavier and temperamental alloy of copper and tin called speculum.
The mounting assembly was also a sight to behold and looked more like a fortification than a piece of scientific apparatus.
This gigantic telescope had a six-foot (1.8 meters) diameter and was used by Lord Rosse for many years to study the night sky. He was particularly interested in the study of 'nebulae' and became the first person to observe the spiral arms of the M51 nebula.
It fell into disuse in the latter half of the 19th Century and was dismantled in 1908. It was, however, reconstructed in the late 1990's by the present Earl.
8. The Yerkes Observatory, Wisconsin pushed the limit
The Yerkes Observatory in Williams Bay, Wisconsin was founded by George Ellery Hale and paid for by Charles T. Yerkes. It would become the world's largest refracting telescope at the time in 1897.
The telescope and housing are a true melding of science and art and calls itself "the birthplace of astrophysics". Yerkes marks a significant change in thinking around telescopes from an amateur hobby to dedicated and serious scientific rigor.
This telescope pushed the limits of the maximum size of refracting telescopes as it used the biggest lenses possible before the entire apparatus would collapse under its own weight. The telescopes lens is an impressive 102 cm diameter doublet lens which is still the largest of its kind used for astronomy.
Partly because of this, many astronomers finally realized that the future of large telescopes had to use mirrors rather than lenses.
The facility has been used by many famous astronomers in history including none other than Edwin Hubble, Subrahmanyan Chandrasekhar, Russian-American astronomer Otto Struve, Gerard Kuiper, and the great Carl Sagan.
9. The radio telescope is born
Radio Telescopy was born in the early 1930's when a Bell Telephone Laboratories engineer, Karl Guthe Jansky, was tasked with finding the source of static that interfered with radio and telephone services. Jansky built an array of dipoles and reflectors that were designed to receive a shortwave radio signal at around 20.5 MHz.
The entire apparatus was set up on a turntable allowing it to turn a full 360 degrees. Jansky's "merry-go-round", as it came to be known, measured 30 meters in diameter and stood at 6 meters tall.
Using this apparatus he was able to determine three types of interference:--
- Nearby thunderstorm static
- Distant thunderstorm static
- A curious constant background "faint hiss" that repeated in a cycle
Jansky correctly suspected this last one originated from outside our solar system with its source coming roughly from the constellation of Sagittarius.
Amateur radio enthusiast, Grote Reber, inspired by Jansky's work would go on to develop the first device to 'see' the radio waves. He did this by building the first parabolic 'dish' telescope that had a diameter of 9 meters in his back garden in Wheaton, Ilinois in 1937.
He repeated Jansky's pioneering work, identifying the Milky Way as the first off-world radio source, and he went on to conduct the first sky survey at very high radio frequencies, discovering other radio sources.
10. Lovell's telescope takes radio telescopes to a whole new level
Building on the pioneering work of Jansky and Grote, British Astronomer Sir Bernard Lovell made plans to build a large radio telescope in the 1950's. After working on radar during the Second World War, Bernard saw the great scientific potential of radio telescopes in studying the cosmos.
His vision was to build a huge 250-foot (76 meters) diameter dish radio telescope that could be aimed at any point in the sky. After a series of big technical and more importantly, financial problems, it was finally built in the summer of 1957 at Jodrell Bank in the UK.
This iconic scientific apparatus has since played an important role in the research of meteors, quasars, pulsars, and was heavily involved with the tracking of space probes at the start of the Space Age.
11. Hubble Space Telescope
In 1990, NASA and ESA co-operated to build and deploy the Hubble Space Telescope making it one of the first telescope to be launched into space. Although not the first space telescope, Hubble has is one of the largest an most flexible.
Since its deployment into low earth orbit, it has taken part in many vital research projects and PR for the field of astronomy in general. Liberated from the distortion of Earth's atmosphere (and limited background light), Hubble can provide very clear images of the stars and planets unparalleled from Earth.
The telescope consists of a 2.4-meter mirror and a suite of other instruments to observe near UV, visible light and near IR spectra. Hubble should be able to stay in service well into the 2030's.
12. The Compton Gamma Ray Observatory was a game-changer
In 1991, a revolutionary space telescope was deployed into space with the goal of detecting photons with energies between 20 keV and 30n GeV. Called the Compton Gamma Ray Observatory (CGRO), it consists of four telescopes on a single platform that observed X-rays and gamma rays.
After a long development period, CGRO was delivered into low Earth orbit by the Space Shuttle Atlantis during the STS-37 mission in April 1991. It continued operations until its deorbit in June 2000.
CGRO was the heaviest astrophysical payload ever flown at that time at 17,000 kilograms and cost around $617 million to develop.
Along with the Hubble Space Telescope, CGRO formed part of NASA's ''Great Observatories" series of telescopes.
13. The W. M. Keck Observatory is the world's second-largest telescope
Currently, the second largest telescopes in the world, the W. M. Keck Observatory is a twin-telescope astronomical observatory near the summit of Mauna Kea in Hawaii. It is built at an incredible 13,600 feet (4145 meters) above sea level and offers unparalleled Earthbound views of the cosmos.
Proposed in 1977, both of its telescopes comprise 10-meter primary mirrors and it was built between 1990 and 1996. The primary breakthrough necessary to build such large mirrors was the concept of using smaller, usually hexagonal, mirror segments to form a larger contiguous mirror.
In the case of the Keck telescopes, each mirror comprises 36 segments, each 1.8 meters wide, 7.5 meters thick and weighing half a ton.
14. The Herschel Space Observatory was the largest infrared telescope ever sent into space
Active between 2009 and 2013, the Herschel Space Observatory was built by the European Space Agency. It was the largest ever infrared telescope to be launched into space.
Its operational window was so short due to its limited supply of coolant for its vital instruments.
It consisted of a 3.5-meter mirror with other highly specialized instruments sensitive to far infrared and submillimeter wavebands between 55 and 672 micrometers. The Herschel Space Observatory formed the final component of the Horizon 2000 programme along with SOHO/Cluster II, XMM-Newton and Rosetta.
The space telescope was primarily built to observe the coldest and dustiest objects in space. Especially looking for areas of solar genesis in areas where dusty galaxies were likely to start forming new stars.
15. The James Webb Space Telescope will replace the aging Hubble Telescope
The James Webb Space Telescope, developed by NASA, the ESA and the Canadian Space Agency is intended to replace the aging Hubble Space Telescope and will offer unprecedented imagery of the cosmos once deployed.
Once in space, it will offer unprecedented resolution and sensitivity and provide a broad range of investigative abilities that should yield important data for astrophysicists and cosmologists.
In March 2018, NASA delayed the JWST's launch an additional year after the telescope's sun shield ripped during a practice deployment and the sun shield's cables did not sufficiently tighten. Deployment is now scheduled for launch in May 2020 from French Guiana.
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