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96-464: The observatory, often called "the birthplace of modern astrophysics", was founded in 1892 by astronomer George Ellery Hale and financed by businessman Charles T. Yerkes . It represented a shift in the thinking about observatories, from their being mere housing for telescopes and observers, to the early-20th-century concept of observation equipment integrated with laboratory space for physics and chemistry analysis. The observatory's main dome houses

192-482: A focal point ; while those not parallel converge upon a focal plane . The telescope converts a bundle of parallel rays to make an angle α, with the optical axis to a second parallel bundle with angle β. The ratio β/α is called the angular magnification. It equals the ratio between the retinal image sizes obtained with and without the telescope. Refracting telescopes can come in many different configurations to correct for image orientation and types of aberration. Because

288-462: A 40 in-diameter (102 cm) doublet lens refracting telescope , the second-largest refractor ever successfully used for astronomy. The largest lens is the Swedish 1-m Solar Telescope . There are several smaller telescopes – some permanently mounted – that are primarily used for educational purposes. The observatory also holds a collection of over 170,000 photographic plates. The Yerkes 40-inch

384-553: A 91 cm lens. Prior to its installation, the telescope on its enormous German equatorial mount was shown at the World's Columbian Exhibition in Chicago, Illinois during the time the observatory was under construction. The observatory was a center for serious astronomical research for more than 100 years. By the 21st century, however, the historic telescope had reached the end of its research life. The University of Chicago closed

480-462: A center for research for decades afterwards. In addition to the large refractor, Yerkes also conducted a great amount of Solar observations. Yerkes Observatory's 40-inch (102 cm) refracting telescope has a doublet lens produced by the optical firm Alvan Clark & Sons and a mounting by the Warner & Swasey Company . It was the largest refracting telescope used for astronomical research. In

576-508: A considerable fortune manufacturing and installing passenger elevators during the reconstruction of Chicago, which had been destroyed in the Great Chicago Fire of 1871. The oldest of three children who lived past childhood, George received strong encouragement from his father, who supported the boy's active mind and curiosity, and his mother, who inculcated in him a love of poetry and literature. He spent his youth fascinated by

672-430: A couple of years. Apochromatic refractors have objectives built with special, extra-low dispersion materials. They are designed to bring three wavelengths (typically red, green, and blue) into focus in the same plane. The residual color error (tertiary spectrum) can be an order of magnitude less than that of an achromatic lens. Such telescopes contain elements of fluorite or special, extra-low dispersion (ED) glass in

768-563: A course in shop-work at the Chicago Manual Training School. During these years, Hale developed a knowledge of the principles of architecture and city planning with the help of his father's friend, well-known architect Daniel Burnham . Upon Burnham's advice and encouragement, Hale decided at the age of seventeen to continue his education at the Massachusetts Institute of Technology (MIT). Hale

864-731: A few months at a sanatorium in Maine. These problems forced him to resign as director of Mount Wilson. He died at the Las Encinas Sanitarium in Pasadena in 1938. Fox Mulder uses the pseudonym "George E. Hale" on several occasions in the TV series The X-Files , most notable in Season 2, Episode 1 "Little Green Men", and Season 2, Episode 4 "Sleepless". Check It Out! with Dr. Steve Brule has an episode on "space" which references

960-450: A few months because of health problems. He was replaced by his colleague Robert Andrew Millikan . Hale suffered from neurological and psychological problems, including insomnia , frequent headaches, and depression. The often-repeated myth of schizophrenia , alleging he claimed to have regular visits from an elf who acted as his advisor, arose from a misunderstanding by one of his biographers. He occasionally took time off to spend

1056-469: A foot on each side. The Bruce astrograph lenses were made by Brashear with Mantois of Paris glass blanks, and the lenses were completed by the year 1900. The overall telescope was not completed until 1904, where it was installed in its own dome at Yerkes. The astronomer Edward Emerson Barnard 's work with the Bruce telescope, with his niece Mary R. Calvert who worked as his assistant and computer, lead to

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1152-599: A good reputation compared to speculum metal and silver on glass mirror telescopes, which had not quite proven themselves in the 1890s. For example, the Leviathan of Parsonstown was a 1.8 meter telescope with a speculum metal mirror, but getting good astronomical results from this technology could be difficult. Another large telescope of this period was the Great Melbourne Telescope in Australia, also

1248-559: A group of local residents, submitted an expression of interest to the University of Chicago with a proposal that would seek to maintain public access to the site and continuation of the educational programs. Transfer of operation to a successor operator was not arranged by the end of August, and the facility was closed to the general public on October 1. Some research activities continued at the Observatory, including access and use of

1344-818: A key role in the foundation of the International Union for Cooperation in Solar Research and the National Research Council , and in developing the California Institute of Technology into a leading research university. George Ellery Hale was born on June 29, 1868, in Chicago , Illinois, to William Ellery Hale and Mary Browne. He is descended from Thomas Hale of Watton-on-Stone, Hertfordshire , England, whose son emigrated to America about 1640. His father acquired

1440-402: A metal mirror telescope. Some of the instruments for the 40-inch refractor (circa 1890s) were: The 40-inch refractor was modernized in the late 1960s with electronics of the period. The telescope was painted, the manual controls were removed, and electric operations were added at that time. This included nixie tube displays for its operation. In the late 1960s a 40-inch reflecting telescope

1536-540: A narrow field of view. Despite these flaws, the telescope was still good enough for Galileo to explore the sky. He used it to view craters on the Moon , the four largest moons of Jupiter , and the phases of Venus . Parallel rays of light from a distant object ( y ) would be brought to a focus in the focal plane of the objective lens ( F′ L1 / y′ ). The (diverging) eyepiece ( L2 ) lens intercepts these rays and renders them parallel once more. Non-parallel rays of light from

1632-496: A non-inverted (i.e., upright) image. Galileo's most powerful telescope, with a total length of 980 millimeters (39 in; 3 ft 3 in; 1.07 yd; 98 cm; 9.8 dm; 0.98 m), magnified objects about 30 times. Galileo had to work with the poor lens technology of the time, and found he had to use aperture stops to reduce the diameter of the objective lens (increase its focal ratio ) to limit aberrations, so his telescope produced blurry and distorted images with

1728-733: A permanent international scientific organization; the new union had its first constituted meeting at Oxford in England a year later. Further meetings were held in Paris in 1907 and at Mount Wilson in 1910, where the purview of the Union was enlarged to include stellar research, in keeping with Hale's emphasis on the Sun as just one among the many other stars. Shortly after the last meeting in Bonn in 1913, World War I broke out, which effectively put an end to

1824-462: A real fact about Hale in passing. Refracting telescope A refracting telescope (also called a refractor ) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope ). The refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses . Although large refracting telescopes were very popular in

1920-529: A refracting telescope appeared in the Netherlands about 1608, when a spectacle maker from Middelburg named Hans Lippershey unsuccessfully tried to patent one. News of the patent spread fast and Galileo Galilei , happening to be in Venice in the month of May 1609, heard of the invention, constructed a version of his own , and applied it to making astronomical discoveries. All refracting telescopes use

2016-563: A refracting telescope is around 1 meter (39 in). There is a further problem of glass defects, striae or small air bubbles trapped within the glass. In addition, glass is opaque to certain wavelengths , and even visible light is dimmed by reflection and absorption when it crosses the air-glass interfaces and passes through the glass itself. Most of these problems are avoided or diminished in reflecting telescopes , which can be made in far larger apertures and which have all but replaced refractors for astronomical research. The ISS-WAC on

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2112-475: A roughly seven foot long skeleton truss made of aluminum. At one point the Observatory had an IBM 1620 computer, which it used for three years. This was replaced with an IBM 1130 computer in the 1960s. A microphotometer was built by Gaertner Scientific Corporation, which was delivered in February 1968 to the observatory. Later, there was another 24-inch reflecting telescope by Boller & Chivens. This

2208-541: Is 1024 Hale , provisional designation A923 YO 13 , a carbonaceous background asteroid from the outer regions of the asteroid belt , approximately 45 km (28 mi) in diameter. The asteroid was discovered on 2 December 1923 by Belgian–American astronomer George Van Biesbroeck at Yerkes Observatory, and it was named for astronomer George Ellery Hale of Yerkes Observatory fame. Some additional examples include 990 Yerkes , 991 McDonalda , and 992 Swasey around this time; many more minor planets would be discovered at

2304-533: Is also famed for its design work by Olmsted. The observatory building was designed by architect Henry Ives Cobb , and has been referred to as being in the Beaux Arts style. The building is noted for its blend of styles and rich ornamentation featuring a variety of animal and mythological designs. On the building there are various carvings including Lion gargoyle designs. There are also sculptures to represent various people that oversaw or supported construction of

2400-404: Is an improvement on Galileo's design. It uses a convex lens as the eyepiece instead of Galileo's concave one. The advantage of this arrangement is that the rays of light emerging from the eyepiece are converging. This allows for a much wider field of view and greater eye relief , but the image for the viewer is inverted. Considerably higher magnifications can be reached with this design, but, like

2496-683: Is based on spectral lines sensitive to stellar temperature and surface gravity , which are related to luminosity (the Harvard classification is based on surface temperature). Later, in 1953, after some revisions of lists of standard stars and classification criteria, the scheme was named the Morgan–Keenan classification , or MK. Research work of the Yerkes Observatory has been cited over 10,000 times. In 1899, observations of Neptune's moon Triton were published, with data recorded using

2592-435: Is ground and polished , and then the two pieces are assembled together. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus in the same plane. Chester More Hall is noted as having made the first twin color corrected lens in 1730. Dollond achromats were quite popular in the 18th century. A major appeal was they could be made shorter. However, problems with glass making meant that

2688-427: Is likely to show considerable color fringing (generally a purple halo around bright objects); an f / 16 achromat has much less color fringing. In very large apertures, there is also a problem of lens sagging , a result of gravity deforming glass . Since a lens can only be held in place by its edge, the center of a large lens sags due to gravity, distorting the images it produces. The largest practical lens size in

2784-493: Is noted as a precursor to the founding of the American Astronomical Society . Although dedicated in 1897, it was founded in 1892. Also, astronomical observations had started in the summer of 1897 before the dedication. Research conducted at Yerkes in the last decade includes work on the interstellar medium , globular cluster formation, infrared astronomy, and near-Earth objects . Until recently,

2880-471: Is now commonly referred to as the " Hale–Nicholson law ," or in many cases simply "Hale's law." Hale spent a large portion of his career trying to find a way to image the solar corona without the benefit of a total solar eclipse, but this was not achieved until the work of Bernard Lyot . In October 1913, Hale received a letter from Albert Einstein , asking whether certain astronomical observations could be done that would test Einstein's hypothesis concerning

2976-406: Is one factor that increased the site's development in the following decades. The editorial offices for The Astrophysical Journal were located at Yerkes Observatory until the 1960s. The landscape was designed by the same firm that designed New York Central park , the firm of Frederick Law Olmsted, and the grounds were noted at one point for having multiple state record trees. The tree plan design

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3072-682: Is the Shuckburgh telescope (dating to the late 1700s). A famous refractor was the "Trophy Telescope", presented at the 1851 Great Exhibition in London. The era of the ' great refractors ' in the 19th century saw large achromatic lenses, culminating with the largest achromatic refractor ever built, the Great Paris Exhibition Telescope of 1900 . In the Royal Observatory, Greenwich an 1838 instrument named

3168-605: The Galilean satellites of Jupiter in 1610 with a refracting telescope. The planet Saturn's moon, Titan , was discovered on March 25, 1655, by the Dutch astronomer Christiaan Huygens . In 1861, the brightest star in the night sky, Sirius, was found to have smaller stellar companion using the 18 and half-inch Dearborn refracting telescope. By the 18th century refractors began to have major competition from reflectors, which could be made quite large and did not normally suffer from

3264-676: The Kenwood Astrophysical Observatory , which Hale's father had built for him; he was professor of astrophysics at Beloit College (1891–93); associate professor at the University of Chicago until 1897, and full professor (1897–1905). He was coeditor of Astronomy and Astrophysics , 1892–95, and after 1895 editor of the Astrophysical Journal . He also served on the board of trustees for Science Service, now known as Society for Science &

3360-561: The Kuiper belt , home to dwarf planet Pluto), Nancy Grace Roman , NASA's first Chief of Astronomy (who did her graduate work at Yerkes), and the twentieth-century popularizer of astronomy Carl Sagan . In 2022, astronomer Dr. Amanda Bauer was the first astronomer hired by the Yerkes Future Foundation, which took over the observatory, its restoration and operation from the University of Chicago in 2020. She came to Yerkes from

3456-517: The Sheepshanks telescope includes an objective by Cauchoix. The Sheepshanks had a 6.7-inch (17 cm) wide lens, and was the biggest telescope at Greenwich for about twenty years. An 1840 report from the Observatory noted of the then-new Sheepshanks telescope with the Cauchoix doublet: The power and general goodness of this telescope make it a most welcome addition to the instruments of

3552-643: The University of Chicago also maintained an engineering center in the observatory, dedicated to building and maintaining scientific instruments. In 2012 the engineers completed work on the High-resolution Airborne Wideband Camera (HAWC), part of the Stratospheric Observatory for Infrared Astronomy (SOFIA). Researchers also use the Yerkes collection of over 170,000 archival photographic plates that date to

3648-551: The Vera Rubin Telescope , then under construction in Chile, and was appointed the first-ever Montgomery Foundation Deputy Director and Head of Science and Education. Visitors: Directors of Yerkes Observatory: In 2006, the University of Chicago announced plans to sell the observatory and its land to a developer. Under the plan, a 100-room resort with a large spa operation and attendant parking and support facilities

3744-606: The Voyager 1 / 2 used a 6 centimetres (2.4 in) lens, launched into space in the late 1970s, an example of the use of refractors in space. Refracting telescopes were noted for their use in astronomy as well as for terrestrial viewing. Many early discoveries of the Solar System were made with singlet refractors. The use of refracting telescopic optics are ubiquitous in photography, and are also used in Earth orbit. One of

3840-572: The moons of Mars in 1877. There was an extraordinary increase of larger telescopes in finely furnished observatories in the late 1800s. In the 1890s various forces came together to establish an observatory of art, science, and superlative instruments in Williams Bay, Wisconsin. The telescope was surpassed by the Harvard College Observatory, 60 in (152 cm) reflector less than ten years later, although it remained

3936-530: The sun . From early youth, Hale had been internationally oriented, travelling widely throughout Europe in his younger years. Having long realized the value of an international organization to coordinate scientific research, he pursued, as chairman of a committee of the National Academy of Sciences of the US, the formation of an international organization for solar research. The society's inaugural meeting

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4032-656: The 1890s. The past few years have seen astronomical research largely replaced by educational outreach and astronomical tourism activities. In June 1967, Yerkes Observatory hosted the to-date largest meeting of the American Astronomical Society, with talks on over 200 papers. The Yerkes spectral classification (aka MKK system) was a system of stellar spectral classification introduced in 1943 by William Wilson Morgan , Philip C. Keenan , and Edith Kellman from Yerkes Observatory. This two-dimensional ( temperature and luminosity ) classification scheme

4128-520: The 1893 World's Columbian Exposition in Chicago before being installed in the observatory. The grinding of the lens was completed later. The glass blanks for what would become Yerkes Great Refractor were made in Paris, France by Mantois and delivered to Alvan Clark & Sons in Massachusetts where they were completed. Clark then made what would be the largest telescope lens ever crafted and this

4224-584: The 21st century to observe the Sun. Another instrument was the Bruce photographic telescope. The telescope had two objective lenses for photography, one doublet of 10 inches aperture and another of 6.5 inches; in addition there is a 5-inch guide scope for visual viewing. The telescope was constructed from funds donated in 1897. The telescope was mounted on a custom designed equatorial, the result of collaboration between Yerkes and Warner & Swasey, especially designed to offer an uninterrupted tracking for long image exposures. The images were taken on glass plates about

4320-458: The Galilean telescope, it still uses simple single element objective lens so needs to have a very high focal ratio to reduce aberrations ( Johannes Hevelius built an unwieldy f/225 telescope with a 200-millimetre (8 in) objective and a 46-metre (150 ft) focal length , and even longer tubeless " aerial telescopes " were constructed). The design also allows for use of a micrometer at

4416-560: The Public , from 1921 to 1923. In 1908, he used the Zeeman effect with a modified spectroheliograph to establish that sunspots were magnetic. Subsequent work demonstrated a strong tendency for east-west alignment of magnetic polarities in sunspots, with mirror symmetry across the solar equator; and that the polarity in each hemisphere switched orientation from one sunspot cycle to the next. This systematic property of sunspot magnetic fields

4512-557: The Union's activities. Work continued after the 1919 founding of the International Astronomical Union . During the war, Hale played a key role in founding the National Research Council to support the government in using science for its policy aims, in particular to further its military ends. In 1922, he was appointed at the League of Nations ' Committee on Intellectual Cooperation but had to resign after

4608-609: The Warner & Swasey micrometer. In 1898 and 1899, Neptune was at opposition. In 1906, a star catalog of over 13,600 stars was published. Also, there was important work on Solar research in the early years, which was of interest to Hale. He went on to the Snow Solar Telescope at Mount Wilson in California. This was first operated at Yerkes and then moved to California. An example of an asteroid discovered at Yerkes

4704-403: The books and machinery given to him by his parents—one of his most prized possessions was a small microscope . With his father's encouragement, he built a small shop in their house that turned into a laboratory. The microscope led to his interest in optics. At the age of fourteen, George built his first telescope. His father later replaced it with a second-hand Clark refractor that they mounted on

4800-640: The effects of gravity on light. Hale replied in November, saying that such observations could be done only during a total eclipse of the Sun . Hale was a driven individual, who worked to found a number of significant astronomical observatories, including Yerkes Observatory , Mount Wilson Observatory , Palomar Observatory , and the Hale Solar Laboratory . At Mount Wilson, he hired and encouraged Harlow Shapley and Edwin Hubble toward some of

4896-404: The extensive historical glass plate archives at the site. Yerkes education and outreach staff formed a nonprofit organization – GLAS – to continue their programs at another site after the closing. In May 2019, the university continued to negotiate with interested parties on Yerkes's future, primarily with the Yerkes Future Foundation. It was announced in November 2018 that a sticking point had been

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4992-640: The famous triplet objectives is the Cooke triplet , noted for being able to correct the Seidal aberrations. It is recognized as one of the most important objective designs in the field of photography. The Cooke triplet can correct, with only three elements, for one wavelength, spherical aberration , coma , astigmatism , field curvature , and distortion . Refractors suffer from residual chromatic and spherical aberration . This affects shorter focal ratios more than longer ones. An f /6 achromatic refractor

5088-580: The first commissioned outdoor sculpture by artist Ashley Zelinskie . Yerkes has hosted talks, programs or residencies with Grammy-winning musicians and composers Eighth Blackbird , Brooklyn-based artist Ashley Zelinskie , former US Poet Laureate Tracy K Smith , astronomer and public educator Dean Regas , and former Senior Scientist of the James Webb Space Telescope and Nobel prizewinner Dr. John Mather . Major restoration work has been ongoing and will continue for many years ahead. Since

5184-436: The focal plane (to determine the angular size and/or distance between objects observed). Huygens built an aerial telescope for Royal Society of London with a 19 cm (7.5″) single-element lens. The next major step in the evolution of refracting telescopes was the invention of the achromatic lens , a lens with multiple elements that helped solve problems with chromatic aberration and allowed shorter focal lengths. It

5280-578: The glass objectives were not made more than about four inches (10 cm) in diameter. In the late 19th century, the Swiss optician Pierre-Louis Guinand developed a way to make higher quality glass blanks of greater than four inches (10 cm). He passed this technology to his apprentice Joseph von Fraunhofer , who further developed this technology and also developed the Fraunhofer doublet lens design. The breakthrough in glass making techniques led to

5376-598: The goal to $ 40million. The mission of Yerkes is to "...advance humankind's understanding of the universe and our place within it, igniting curiosity, facilitating exploration, and nurturing a deep sense of connection with our environment, our planet and each other." The foundation has taken steps to transform the observatory and its grounds into a unique public site for astronomy and discovery, hosting researchers and graduate students in astronomy, offering public talks and programs, tours and education programs. In 2023, Yerkes opened four newly-built miles of walking trails and installed

5472-578: The great refractors of the 19th century, that became progressively larger through the decade, eventually reaching over 1 meter by the end of that century before being superseded by silvered-glass reflecting telescopes in astronomy. Noted lens makers of the 19th century include: Some famous 19th century doublet refractors are the James Lick telescope (91 cm/36 in) and the Greenwich 28 inch refractor (71 cm). An example of an older refractor

5568-423: The image was formed by the bending of light, or refraction, these telescopes are called refracting telescopes or refractors . The design Galileo Galilei used c.  1609 is commonly called a Galilean telescope . It used a convergent (plano-convex) objective lens and a divergent (plano-concave) eyepiece lens (Galileo, 1610). A Galilean telescope, because the design has no intermediary focus, results in

5664-408: The more famous applications of the refracting telescope was when Galileo used it to discover the four largest moons of Jupiter in 1609. Furthermore, early refractors were also used several decades later to discover Titan, the largest moon of Saturn, along with three more of Saturn's moons. In the 19th century, refracting telescopes were used for pioneering work on astrophotography and spectroscopy, and

5760-566: The most significant discoveries of the time. He was a prolific organizer who helped create a number of astronomical institutions, societies and journals. Hale also played a central role in developing the California Institute of Technology into a leading research university. After retiring as director at Mount Wilson, he built the Hale Solar Laboratory in Pasadena, California , as his office and workshop, pursuing his interest in

5856-445: The need to include the Yerkes family in the discussions. Mr. Yerkes's agreement in making his donation to the university transfers ownership "To have and to hold unto the said Trustees [of the University of Chicago] and their successors so long as they shall use the same for the purpose of astronomical investigation, but upon their failure to do so, the property hereby conveyed shall revert to the said Charles T. Yerkes or his heirs at law,

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5952-450: The object traveling at an angle α1 to the optical axis travel at a larger angle ( α2 > α1 ) after they passed through the eyepiece. This leads to an increase in the apparent angular size and is responsible for the perceived magnification. The final image ( y″ ) is a virtual image, located at infinity and is the same way up (i.e., non-inverted or upright) as the object. The Keplerian telescope , invented by Johannes Kepler in 1611,

6048-433: The objective and produce a very crisp image that is virtually free of chromatic aberration. Due to the special materials needed in the fabrication, apochromatic refractors are usually more expensive than telescopes of other types with a comparable aperture. In the 18th century, Dollond, a popular maker of doublet telescopes, also made a triplet, although they were not really as popular as the two element telescopes. One of

6144-470: The observatory In the 1900s a noted optics maker was Zeiss. An example of prime achievements of refractors, over 7 million people have been able to view through the 12-inch Zeiss refractor at Griffith Observatory since its opening in 1935; this is the most people to have viewed through any telescope. Achromats were popular in astronomy for making star catalogs, and they required less maintenance than metal mirrors. Some famous discoveries using achromats are

6240-530: The observatory in October 2018. In November 2019, it was announced that the university would transfer Yerkes Observatory to the non-profit Yerkes Future Foundation (YFF). The transfer of ownership took place on May 1, 2020. The community-based foundation hired a director and launched a $ 25M campaign to restore the observatory and the fifty acres of historic Olmsted-designed grounds. By 2024 the foundation had already raised some $ 21million towards its goal, and extended

6336-569: The observatory in the following decades. Notable astronomers who conducted research at Yerkes include Albert Michelson , Edwin Hubble (who did his graduate work at Yerkes and for whom the Hubble Space Telescope was named), Subrahmanyan Chandrasekhar (for whom the Chandra Space Telescope was named), Ukrainian-American astronomer Otto Struve , Dutch-American astronomer Gerard Kuiper (noted for theorizing

6432-560: The observatory re-opened to the public in summer 2022 for tours and programs, more than 50,000 ticketed visitors have taken tours or attended events, with tens of thousands more enjoying the open-access landscape. In the 1860s Chicago became home of the largest telescope in America, the Dearborn 18 + 1 ⁄ 2  in (47 cm) refractor. It was later surpassed by the U.S. Naval Observatory 's 26 inch, which would go on to discover

6528-527: The planet Neptune and the Moons of Mars . The long achromats, despite having smaller aperture than the larger reflectors, were often favored for "prestige" observatories. In the late 18th century, every few years, a larger and longer refractor would debut. For example, the Nice Observatory debuted with 77-centimeter (30.31 in) refractor, the largest at the time, but was surpassed within only

6624-430: The pre-1925 astronomical convention that began the day at noon, give the time of discovery as 11 August 14:40 and 17 August 16:06 Washington mean time respectively). The telescope used for the discovery was the 26-inch (66 cm) refractor (telescope with a lens) then located at Foggy Bottom . In 1893 the lens was remounted and put in a new dome, where it remains into the 21st century. Jupiter's moon Amalthea

6720-469: The publication of a sky atlas using images taken with the instrument, and also a catalog of dark nebulae known as the Barnard catalog . The Observatory was dedicated on October 21, 1897, and there was a large party with university, astronomers, and scientists. Before the dedication, a conference of astronomers and astrophysicists was hosted at Yerkes Observatory, taking place on October 18–20, 1897. This

6816-420: The rear, where the telescope view comes to focus. Originally, telescopes had an objective of one element, but a century later, two and even three element lenses were made. Refracting telescopes use technology that has often been applied to other optical devices, such as binoculars and zoom lenses / telephoto lens / long-focus lens . Refractors were the earliest type of optical telescope . The first record of

6912-552: The refractors. Despite this, some discoveries include the Moons of Mars, a fifth Moon of Jupiter, and many double star discoveries including Sirius (the Dog star). Refractors were often used for positional astronomy, besides from the other uses in photography and terrestrial viewing. The Galilean moons and many other moons of the solar system, were discovered with single-element objectives and aerial telescopes. Galileo Galilei 's discovered

7008-408: The related instrument, the heliometer, was used to calculate the distance to another star for the first time. Their modest apertures did not lead to as many discoveries and typically so small in aperture that many astronomical objects were simply not observable until the advent of long-exposure photography, by which time the reputation and quirks of reflecting telescopes were beginning to exceed those of

7104-484: The roof of their Kenwood house. Soon he was photographing the night skies, observing a partial eclipse of the Sun, and drawing sunspots. As an avid reader with a strong interest in the budding field of astrophysics, Hale was drawn to the writings of William Huggins , Norman Lockyer , and Ernest Rutherford . His fascination with science, however, did not preclude interests more typical of a normal boy, such as fishing, boating, swimming, skating, tennis, and bicycling. He

7200-473: The same as if this conveyance had never been made." In 2022, the site was re-opened to visitors. In 2023, Amanda Bauer was interviewed and demonstrated the use of the telescope, partly restored. Full restoration was expected to take 10 more years. The Observatory grounds and buildings are renowned for more than the Great Refractor, but also sculptures and architecture. In addition, the landscaping

7296-610: The same inherent problem with chromatic aberration. Nevertheless, the astronomical community continued to use doublet refractors of modest aperture in comparison to modern instruments. Noted discoveries include the Moons of Mars and a fifth moon of Jupiter, Amalthea . Asaph Hall discovered Deimos on 12 August 1877 at about 07:48 UTC and Phobos on 18 August 1877, at the US Naval Observatory in Washington, D.C. , at about 09:14 GMT (contemporary sources, using

7392-411: The same principles. The combination of an objective lens 1 and some type of eyepiece 2 is used to gather more light than the human eye is able to collect on its own, focus it 5 , and present the viewer with a brighter , clearer , and magnified virtual image 6 . The objective in a refracting telescope refracts or bends light . This refraction causes parallel light rays to converge at

7488-415: The second half of the 19th century, for most research purposes, the refracting telescope has been superseded by the reflecting telescope , which allows larger apertures . A refractor's magnification is calculated by dividing the focal length of the objective lens by that of the eyepiece . Refracting telescopes typically have a lens at the front, then a long tube , then an eyepiece or instrumentation at

7584-417: The telescope and the facility. The location is noted for a good and pleasant location by Lake Geneva. Although it does not have a high-altitude as preferred by modern observatories, it does have good weather, and is a considerable distance from the light and pollution of Chicago. In 1888, Williams Bay had a railway terminal added by Chicago & North Western Railroad ; this provided access from Chicago, and

7680-493: The years following its establishment, the bar was set and tried to be exceeded; an even larger demonstration refractor, the Great Paris Exhibition Telescope of 1900 , was exhibited at the Paris Universal Exhibition of 1900 . However, this was not much of a success, was dismantled, and did not become part of an active University observatory. The mounting and tube for the 40-inch telescope was exhibited at

7776-478: The zoning from education to residential caused the developer to abandon its development plans. In view of the public controversy surrounding the development proposals, the university suspended these plans in January 2007. In March 2018, the University of Chicago announced that it would no longer operate the observatory after October 1, 2018, and would be seeking a new owner. In May 2018, the Yerkes Future Foundation,

7872-469: Was CER-VII. The launch instruments for the 41 inch reflector included: The reflector is of the Ritchey - Chretien optical design. The 41-inch helped pioneer the field of adaptive optics. A 12-inch refractor was moved to Yerkes from Kenwood Observatory in the 1890s. Two other telescopes planned for the observatory in the 1890s were a 12-inch aperture refractor and a 24-inch reflecting telescope. There

7968-514: Was a heliostat mirror and a meridian room for a transit instrument . A two-foot aperture reflecting telescope was manufactured at the observatory itself. The clear aperture of the telescope was actually 23.5 inches. The glass blanks were cast in France by Saint Gobain Glass Works, and then were figured (polished into telescopic shape) at the Yerkes Observatory. The 'Two foot telescope' used

8064-420: Was added to the observatory complex. The 41 inch was finished by 1968, with overall installation completed by December 1967 and the optics in 1968. While the telescope has a clear aperture of 40-inches, the mirror's physical diameter measures 41-inches leading to the telescope usually being called the "41 inch" to avoid confusion with the 40 inch refractor. The mirror is made from low-expansion glass. The glass used

8160-413: Was also at Yerkes Observatory. The Snow Solar Telescope was first established at Yerkes Observatory, and then moved in 1904 to California. A major difficulty of these telescopes was dealing with heat from the Sun. It was built horizontally but led to a vertical solar tower design afterwards. Solar tower telescopes would be a popular style for solar observatories in the 20th century, and are still used in

8256-472: Was an American astrophysicist , best known for his discovery of magnetic fields in sunspots , and as the leader or key figure in the planning or construction of several world-leading telescopes; namely, the 40-inch refracting telescope at Yerkes Observatory , 60-inch Hale reflecting telescope at Mount Wilson Observatory , 100-inch Hooker reflecting telescope at Mount Wilson, and the 200-inch Hale reflecting telescope at Palomar Observatory . He played

8352-559: Was an enthusiastic reader of the stories of Jules Verne —particularly drawn to the tales of adventure set in the mountains of California. Hale spent summers at his grandmother's house in the old New England village of Madison, Connecticut , where he met his future wife, Evelina Conklin. After graduating from Oakland Public School in Chicago, Hale attended the Allen Academy, where he studied chemistry, physics, and astronomy. He supplemented his practical home experience by attending

8448-429: Was contracted in the early 1960s under direction of observatory director W. Albert Hiltner . This telescope was installed in one of the smaller Yerkes domes, and it is known to have been used for visitor programs. This was a design by Boller & Chivens with Cassegrain optical setup, with a 24-inch (61 cm) clear aperture and is on an off-axis equatorial mount. A 7-inch (18 cm) diameter aperture Schmidt camera

8544-535: Was developed in the 1910s under design from the Olmsted firm and with support of the observatory Director; the grounds included the following types of trees at that time: white fir , yellowwood tree , golden rain tree , European beech , fernleaf beech, Japanese pagoda tree , littleleaf linden , Kentucky coffeetree , ginkgo , buckthorn, cut-leaf beeches, and chestnut trees . George Ellery Hale George Ellery Hale (June 29, 1868 – February 21, 1938)

8640-438: Was discovered on 9 September 1892, by Edward Emerson Barnard using the 36 inches (91 cm) refractor telescope at Lick Observatory . It was discovered by direct visual observation with the doublet-lens refractor. In 1904, one of the discoveries made using Great Refractor of Potsdam (a double telescope with two doublets) was of the interstellar medium . The astronomer Professor Hartmann determined from observations of

8736-564: Was educated at MIT , at the Harvard College Observatory , (1889–90), and in Berlin (1893–94) where he was a PhD student but never finished his degree. At the time he already had an appointment as a professor at the recently established University of Chicago. As an undergraduate at MIT, he is known for inventing the spectroheliograph , with which he made his discovery of solar vortices . In 1890, he began research at

8832-601: Was held at the St. Louis Exposition of 1904 and included representatives from 16 national scientific societies, but notably not from the Prussian Academy of Sciences , which had declined the invitation. Instead, German delegates from the German Physical Society were present. The delegates proceeded to appoint a committee that was to create the International Union for Cooperation in Solar Research as

8928-423: Was invented in 1733 by an English barrister named Chester Moore Hall , although it was independently invented and patented by John Dollond around 1758. The design overcame the need for very long focal lengths in refracting telescopes by using an objective made of two pieces of glass with different dispersion , ' crown ' and ' flint glass ', to reduce chromatic and spherical aberration . Each side of each piece

9024-412: Was mounted to an Equatorial mount made by Warner & Swasey for the observatory. The telescope has an aperture of 40 inches (~102 cm) and focal length of 19.3 meters, giving it a focal ratio of f/19. The lens, an achromatic doublet which has two sections to reduce chromatic aberration, weighed 225 kilograms, and was the last big lens made by Clark before he died in 1897. Glass lens telescopes had

9120-537: Was the largest refracting-type telescope in the world when it was dedicated in 1897. During this time, there were many questions about the merits of the various materials used to construct and design telescopes. Another large telescope of this period was the Great Melbourne Telescope , which was a reflector. In the United States, the Lick refractor had just a few years earlier come online in 1888 in California with

9216-503: Was to be located on the 9-acre (36,000 m) virgin wooded Yerkes land on the lakeshore—the last such undeveloped, natural site on Geneva Lake's 21 mi (34 km) shoreline. About 70 homes were to be developed on the upper Yerkes property surrounding the historic observatory. These grounds had been designed more than 100 years previously by John Charles Olmsted , the nephew and adopted son of famed landscape architect Frederick Law Olmsted . Ultimately, Williams Bay's refusal to change

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