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One notable education project of Yerkes' later years was Project SEE (Space Exploration Experience) for students who are blind or visually impaired. 'They were so excited to see one of the moons pass behind Jupiter, then come back out on the other side a while later,' she said. April Whitt, an educator based at the Adler Planetarium in the 1990s, recalled helping students from Chicago observe the motions of Jupiter's moons through the giant refractor.

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In its later years, as research moved to newer telescopes, Yerkes turned to education. (Image credit: Sloan Digital Sky Survey) Yerkes Observatory closes its doors Historical parallax work done at Yerkes helped prepare for the Sloan Digital Sky Survey, a multiyear project using a telescope in New Mexico to map the locations of millions of galaxies outside our Milky Way.Īn image of the newly measured cannonball star SDSS J1128, as taken by the Sloan Digital Sky Survey. Astronomers can review this collection for parallax measurements, or any other research that might make use of a photograph of a particular area of the sky as it appeared years ago. In more recent years, astronomers at Yerkes developed the HAWC (High-resolution Airborne Wideband Camera) to fly on NASA's SOFIA (Stratospheric Observatory for Infrared Astronomy) aircraft as well as the ARC Echelle Spectrograph, an instrument designed to precisely measure many wavelengths of light simultaneously, for the Apache Point Observatory in New Mexico.Īmong the treasures at Yerkes are 170,000 glass photographic plates taken with the 40-inch refractor and the other telescopes starting in the early 1900s and continuing through the century. This information was a key to estimating the distances to the clusters.Īstronomers at Yerkes were also responsible for founding the American Astronomical Society and the respected Astrophysical Journal. In the 1980s, Kyle Cudworth compared photographs of star clusters taken with the 40-inch telescope more than 80 years apart to measure the motions of stars within the clusters.He found surprising brightness changes in the object now known as Hubble's Variable Nebula, or NGC 2261.

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Edwin Hubble worked as a graduate student at Yerkes from 1914 to 1917, using the reflecting telescope at Yerkes to photograph faint nebulae for his doctoral dissertation.

William van Altena built on Schlesinger’s work in the 1970s, using electronic photometers in conjunction with early photographic plates to measure shifts in star positions using the same telescope.

Measuring this tiny shift, called parallax, is the most reliable way to measure a star's distance. He then measured star positions on the photos with a special microscope, looking for any change between one photo and another.

In the observatory’s early years, astronomer Frank Schlesinger developed the technique of estimating star distances by taking photographs of the same stars at six-month intervals with the big refractor.

Yerkes Observatory has contributed to numerous scientific discoveries throughout the 20th century.

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(Image credit: Roger Ressmeyer/Corbis/VCG/Getty Images) (opens in new tab) Science at Yerkes By 1920, the observatory had three additional telescopes whose capabilities complemented those of the big refractor, as well as an array of laboratory instruments for analyzing light and measuring photographs. The observatory opened with a two-day dedication ceremony in October 1897 and served as the home of the University of Chicago's astronomy and astrophysics department until the 1960s.įrom the beginning, Yerkes Observatory was designed to be more than a telescope in a dome it was a comprehensive laboratory for astrophysical research. The wooden floor surrounding the pier that supports the telescope is 75 feet (23 m) across and can be raised or lowered by an electric elevator so that astronomers can reach the eyepiece end of the telescope whether it is pointed high or low in the sky.

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The dome housing the big telescope is 90 feet (27 m) in diameter, according to a pamphlet published by the observatory in 1920. To build the telescope, the university engaged the same team that had built the Lick instrument: Alvan Clark & Sons for the lenses, and the Warner & Swasey Co. A Chicago real estate speculator offered an expanse of land on the shores of Lake Geneva that fit the bill.

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Hale consulted a group of distinguished astronomers to select an observatory location free of pollution from smoke and electric lights, yet within 100 miles (161 kilometers) of Chicago, to keep a strong link with the university's main campus. 'I will spend a million dollars to lick the Lick.' A few weeks later, Yerkes 'exploded with rage' when told that the 'bare necessities' for his observatory would cost $285,375 (about $8 million today), according to an article in the Boone County Journal. 'I don't care what the cost, send me the bill,' Yerkes told journalists at the time.

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