Skip to comments.Yerkes Observatory: Restoring the World’s Largest Refracting Telescope
Posted on 03/17/2023 11:34:30 AM PDT by Sequoyah101
Built by the University of Chicago in 1897 in Williams Bay, Wisconsin, Yerkes Observatory is home to the world’s largest refracting telescope and famous astronomers like George Ellery Hale, Edwin Hubble and Carl Sagan worked and studied there.
...as newer technology emerged the Great Refractor became less relevant, and the university closed the observatory in 2018. A non-profit formed by residents in the nearby Lake Geneva area took control, and in 2020 that group, Yerkes Future Foundation, embarked on a $20 million renovation effort....
Weighing about 82 tons, the Great Refractor is the world’s largest refracting telescope. The University of Chicago transferred ownership of Yerkes Observatory to Yerkes Future Foundation in 2020, leading to plans for restoring the remarkable telescope for research and public viewing.
The 64-foot barrel of the telescope weighs six tons and has two 40-inch diameter lenses.
The Great Refractor’s mount and barrel were featured at the 1893 World’s Fair and assembled at Yerkes Observatory in 1897.
The Great Refractor is supported by a concrete, brick and steel column extending 40 feet into the ground to help protect it from seismic changes.
To help compensate for Earth’s rotation, the telescope pivots on a mount on a pier measuring 65 feet from its base. A small motor on the mount allows the telescope to stay fixed on an object in constant motion.
The telescope features achromatic lenses instead of mirrors used by more modern reflecting telescopes. When the Great Refractor was completed, astronomers switched from refracting to reflecting telescopes, leading to the Great Refractor remaining the world’s largest refracting telescope.
Using the Great Refractor, Yerkes astronomers revolutionized deep-sky astrophotography.
(Excerpt) Read more at grainger.com ...
Following links at the bottom of a very unpleasant article posted in these pages I found this one. A generally wonderful one so much different from the majority of unhappy news we see too frequently these days.
I hope you enjoy it as much as I have. It takes me back 50 years ago to my last family vacation including a visit to Deerfield Village where I engaged the old fellow running the steam power plant two hours while the family tired to find me. The quiet elegance of this old machinery from our heyday of industrial revolution when we could do anything captures evokes certainty, serenity and confidence of a nation lost. Watch the video as the 35 ton observatory floor quietly moves up to the lens of the telescope. Just audacious to move the whole floor instead of a platform. Chutzpah in engineering straight out of a Jules Verne novel.
I am amazed and gratified the funds to restore the facility were raised and the work is still on going. Thank you to the benefactors.
Countless images in old astronomy books were taken with this instrument.
I was lucky enough to visit Yerkes Observatory on a grade school field trip from Oak Park Illinois. Our combined grade school, middle school had an 8” reflector on the roof for the Astronomy Club. While I’m not an astronomer I’ve always had a love of astronomy because of these influences. I think that interest and knowledge made my life a little better. Public schools were a whole lot better in the 60s.
The 15-inch Great Refractor at the Harvard-Smithsonian in Cambridge is much smaller, but still in working condition, and open every Thursday night to visitors. It was the largest in the U.S. in 1847. (There is also a public lecture.) The original bearings for the dome were iron cannonballs, but they were melted down during World War II, and replaced with roller bearings. Two of the cannonballs are still on display, worn elliptical by 93 years of use.
The great refractor was a pioneer in astrophotography.
No need for that stuff in modern public schools where climate change, pronouns, DIE, genders, and porn are standard curricula.
For a number of years I lived a block away from “The Ob” as it was known then. It’s nice to know that the instrument is preserved, but with all the artificial light in the city there’s not much to see.
Respect must be paid to Alvan Clark, who learned to grind lenses in middle age, and produced quite a few for observatories around the country. The 40 objective for the Yerkes was his largest. Working without computers and lasers, it was quite a feat.
I visited it, perhaps 5 years ago, when I was in the area.
As noted, a photo of this scope and photos from it were in every astronomy book of the 50s and 60s (probably earlier).
It’s a classic and one of a kind. It deserves to be preserved even if it isn’t doing much science anymore; it was a trailblazer in its time.
“Respect must be paid to Alvan Clark, who learned to grind lenses in middle age, and produced quite a few for observatories around the country. The 40 objective for the Yerkes was his largest. Working without computers and lasers, it was quite a feat.”
He did that with his hands, too. Worked his fingers to the bone - literally. So his kids took over.
Allegheny Observatory, Part of The University of Pittsburgh, has, I believe, the third largest refractor, called the “Thaw” when I was a student there. It has a 30-inch lens, magnificent.
They also have a large collection of plates which are used in parallax and proper motion calculations. I think they have well over 100,000 plates dating back to the 1920’s or so.
They also have a 13-inch Clark refractor, with a gravity drive. It is shown to visitors along with free, guided tours of the historical place.
Thanks for the heads up. I was scheduled to be there tonight!
I’m a bit under the weather, so I decided to sit it out.
There was a “Messier Marathon” scheduled for tonight, with other amateurs bringing their telescopes. It was going to be an all-nighter, but the weather isn’t going to co-operate. There will be indoor presentations going on, however.
I’m about an hour from there. I haven’t been there since the 80s and was looking forward to it.
Give Elon Musk a call. Fly up where there is no weather.
If only that were possible, Dan….🙂
We just stayed in Prescott, AZ and went by a house that had an observatory in their roof. My buddy lives on the same mountain and said the guy had it built as part of the house but recently sold it. It was pretty impressive for a house.
I’d love to hear it, Dan.
Allan bought a Bible in the ‘50s and began reading it, and by 1985 or so he decided it was all true. He gave his heart to Jesus and was saved.
Now, he realized he needed to become churched. At the time he was teaching and researching at CalTech in Pasadena and living nearby with his wife. Being a scientist, he approached finding a church as a research project (I have this story directly—more than once—from Dr. Hugh Ross, the famous Christian astrophysicist and apologist; Hugh got it directly from Allan).
Allan used the phone book to list every church within twenty miles. Over a period of several weeks, he visited every single one—but did not enter any of them. Instead, he parked outside each one just as their Sunday morning worship service was letting out. Then, he evaluated them using two criteria: were the people carrying Bibles, and were they happy? In this way Allan narrowed his search to six churches.
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