The Allure of Giant Telescopes

Giant telescopes long embodied the promise of groundbreaking discoveries symbolizing progress, technological prowess, and cultural sophistication.

Astronomie populaire: description générale du ciel illustrée de 360 figures, planches en chromolithographie, cartes célestes, etc.Adler Planetarium

Not all giant telescopes have rendered significant results, but projects involving large instruments continue to generate excitement among the scientific community and the public alike.Join the Adler as we examine the promise and reality of large telescopes throughout history.

Johannis Hevelii Machinae coelestis pars prior [-posterior].Adler Planetarium

An Early Giant Telescope

The Polish astronomer Johannes Hevelius assembled this telescope in the city of Danzig (nowadays Gdansk) in the 17th century. The purpose of building such a large instrument was to circumvent chromatic aberration, an optical effect of refractors  resulting in color fringes around the object in view.

  Though ingenious in its design, Hevelius’s giant telescope was difficult to operate resulting in occasional observations only. This illustration, taken from a major astronomical work by Hevelius, suggests that the telescope became a local attraction nonetheless. As would happen with several other giant telescopes constructed in the coming centuries, bigger was not always better. 

Herschel's Forty-Foot Reflecting TelescopeAdler Planetarium

Herschel’s Most Famous Telescope

 This large reflecting telescope (meaning that it captures light with a mirror) has a 40-foot tube and a 48-inch diameter primary mirror. It was made in the late 1780s under the guidance of William Herschel.  Herschel produced several smaller reflecting telescopes of high quality, some of which he used together with his sister Caroline Herschel.

 Despite all the effort put into its conception and assemblage, the 40-foot telescope did not prove substantially superior to Herschel’s smaller instruments. Nevertheless, it become a tourist attraction in England and held the title of the largest telescope in the world for decades. 

Smith's illustrated astronomy : designed for the use of the public or common schools in the United States ; ill. with numerous original diagrams / by Asa Smith.Adler Planetarium

The Race for Great Refractors

This illustration, taken from an astronomy textbook published in the 1840s, shows the large refracting telescope of the Cincinnati Observatory. A list at the bottom of the page highlights the rank of the United States among the nations in possession of what were then the largest telescopes in the world.

Large telescopes, and particularly refractors, came to symbolize the advancement of astronomy, and more broadly, progress and cultural prestige. This led astronomers, cities, and nations to compete for the largest instruments, in what historians have called the “19th-century race for great refractors.” 

Description de l'Observatoire astronomique central de Poulkova / par F.G.W. Struve.Adler Planetarium

Temples of Astronomy

The tip of a large refracting telescope can be seen through the open main dome of the Imperial Observatory of Russia in Pulkovo, near St. Petersburg. Lavishly funded by Tsar Nicolas I and inaugurated in 1839, the Pulkovo Observatory sported the best astronomical instruments available at the time, in a building carefully designed to provide for accurate astronomical observing.

A true temple of astronomy that affirmed the might of the Russian Empire, the Pulkovo Observatory had a great influence on many other observatory projects. A large refracting telescope set up in a dome topping the observatory’s building became a fixture of 19th-century  astronomy. 

The Chicago Astronomical SocietyAdler Planetarium

The Telescope and the Reemerging City

The Chicago Astronomical Society was founded in 1862. Its wealthy sponsors regarded the acquisition of the large telescope shown in this membership certificate as a major step in cementing Chicago’s cultural prestige. Known as the Dearborn Refractor, the instrument was one  of the largest in the world by the mid-1860s. Its early tests revealed the faint companion to the star Sirius, named Sirius B, which later became one of the first stars to be identified as a white dwarf.

Once set up at the Old University of Chicago, failures in dome design and faulty management resulted in a disappointing performance. However, the Dearborn Refractor acquired a new meaning after the Great Chicago Fire of 1871, becoming a symbol of a city under reconstruction, in a renewed quest for economic vigor and cultural respectabilityThe telescope was eventually relocated to Northwestern University and refigured. The original tube and mount have long been on display at the Adler Planetarium.   

The story of the heavensAdler Planetarium

Grand Amateurs with Grand Telescopes

This reflecting telescope, known as the Leviathan (an allusion to a biblical monster), was set up at Birre Castle in Ireland in 1845 by William Parsons, 3rd Earl of Rosse. Parsons was one of the 19th-century “Grand Amateurs,” wealthy individuals with a passion for  astronomy and plenty of resources to invest in the production of large telescopes. 

With a  72-inch diameter mirror, the Leviathan held the status of the largest telescope in the world for decades. It allowed Parsons to discover the spiral structure of the celestial object now known as the Whirlpool Galaxy. This discovery helped pave the way to the concept that the universe contains a multitude of galaxies, and to unveiling the spiral structure of our very own galaxy, the Milky Way. 

The Lick telescope, length 57 feet, diameter of object glass 36 inches, total weight 40 tonsAdler Planetarium

Looking for Immortality

The Great Lick Refractor, shown in the image, is named after the North-American businessman James Lick, who embarked on a quest for a monument to perpetuate his memory. After considering statues of himself and a large pyramid, Lick decided to sponsor the construction of an astronomical observatory housing the largest refracting telescope ever built. 

Lick Observatory was inaugurated in 1886 in Mount Hamilton, California. It set a trend to place astronomical observatories at high altitudes, while inciting other wealthy individuals to have their names associated with large telescopes. Lick did not live long enough to see the observatory completed, but his remains were interred at the base of the large instrument that bears his name.    

"Yerkes Telescope" from Chicago Tribune Art SupplementAdler Planetarium

A Giant Telescope at a World’s Fair

The tube and mount of the largest refracting telescope ever used in astronomical research are shown here in an unusual setting: the Columbian Exposition held in Chicago in 1893, which remains one of the most ambitious world fairs ever hosted.  

Conceived to mark the 400th anniversary of Columbus’s arrival in the so-called new world, it served, above all, to extoll America’s economic progress and Chicago’s ability to rebuild itself as a major urban center after the Great Fire of 1871. 

The telescope was displayed at the fair to affirm the American capabilities in the production of scientific instruments. It was later installed at Yerkes Observatory in Williams Bay, Wisconsin. The undertaking was sponsored by Charles T. Yerkes, an entrepreneur of mixed reputation who saw an opportunity to improve his public image for posterity.  

Lower section of the 100-inch telescope tube, in transport on Mount Wilson.Adler Planetarium

All the Way Up the Mountain

In the 20th century, large reflecting telescopes took the prominent place formerly held by refractors. Mount Wilson Observatory in California played a leading role in that regard, breaking records by harboring first a reflecting telescope with a mirror of 60 inches, and later also a 100-inch  instrument. 

This photograph was taken in 1916 and shows the lower section of the 100-inch telescope tube in transport on Mount Wilson. The assemblage of this large telescope, led by the astronomer George E. Hale, required tackling complex logistics and many technical problems, and raising large amounts of money.

Despite some defects in its primary mirror, the 100-inch telescope proved particularly important in observations that furthered our understanding of the large scale of the universe and its expansion. 

The Prime Focus, 200-Inch TelescopeAdler Planetarium

Visualizing a Telescope in the Making

This conceptual drawing shows an observer sitting at the primary focus (the point to which light rays converge) of the 200-inch reflecting telescope of Palomar Observatory. Completed in 1947, it became the largest telescope in the world. The drawing is part of a series made by the artist, arctic explorer and amateur telescope maker, Russell Porter. 

The production of this unprecedentedly large instrument was an ambitious project that involved several teams working on specific problems, and which progressed slowly through various incidents and setbacks. By bringing all elements together in compelling depictions of what the finalized instrument was meant to look like, Russell’s images helped steer the project towards a successful completion. 

Antennas under the MilkywayAdler Planetarium

Stronger Together

Our eyes can only see part of the light that reaches the Earth. In order to study the universe that is invisible to us, new kinds of telescopes had to be developed. Since the 1930s, astronomers have been using radio telescopes to detect radio waves originating in stars, galaxies, black holes, and other celestial objects.

Radio telescopes normally have large dishes that capture these radio waves and reflect them towards an antenna. Individual radio telescopes can be combined to function as the equivalent to a single instrument with a very large dish. Such is the case of the Atacama Large Millimeter/submillimeter Array (ALMA), located in the Atacama Desert in Chile. Comprising over 60 individual radio telescopes that function as one, a result of an international collaboration between the US, Europe, and East Asia.  

twin telescopes of Keck Observatory in HawaiiAdler Planetarium

Taking Telescopes to Extremes

This image shows the twin telescopes of Keck Observatory in Hawaii. The observatory sits close to the summit of the dormant volcano Mauna Kea, at an altitude of 4,205 metres (13,796 feet). Each of the two telescopes has a primary mirror formed by 36 hexagonal segments, with an overall diameter of 10 meters (32 ft 10 in). Completed in 1996, Keck Observatory is one of the leading observing facilities in the world for astronomical research in visible and infrared light. 

But scientists, engineers, and decision makers have not stopped pursuing the construction of even larger observing complexes similarly located in high altitudes and relying on cutting-edge technology. Major ongoing projects include the Giant Magellan Telescope and the Extremely Large Telescope both to be located in the region of the Atacama Desert in Chile. 

The construction of the so-called Thirty Meter Telescope in Mauna Kea has been controversial, as this is a site with a special cultural meaning for Native Hawaiians where several observatories are already operated by various countries and organizations. 

Hubble Space Telescope in Orbit June 16, 2021Adler Planetarium

Telescopes in Space

Beginning in the late 1960s, telescopes have been launched into space in order to capture forms of light that are filtered by the Earth’s atmosphere. Space telescopes also have the advantage of circumventing light pollution. Launched in 1990, the Hubble Space Telescope, shown here, was the first major instrument of this kind suited to operate with visible light. It significantly deepened our understanding of the universe.

Webb's Primary Mirror Deployed for the Last Time on EarthAdler Planetarium

The James Webb Space Telescope, a part of whose mirror is shown in the image, is poised to take its leading place. Designed to capture infrared light, it promises to further our knowledge of the evolution of galaxies and the conditions for life beyond Earth.  

However, the fact that it is named after a NASA administrator who was purportedly involved in the discrimination of LGTBQ+ people has generated controversy, reminding us that large telescopes are not just research tools, but also monuments of science whose symbolic meanings are no less relevant than their technical capabilities. 


Credits: Story

Thank you to the staff of the Adler Planetarium for their assistance in creating this exhibition.  Special thanks to our generous supporters:
Amy and Steve Louis Foundation
Roderick and Marjorie Webster Fund at The Chicago Community Trust

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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