Sunday Concerts Under the 100-inch Telescope Dome!

For the first half of the 20th Century, Mount Wilson was the most famous observatory in the world. The biggest telescopes were here, and their new designs were changing the way astronomy was done. Among the many discoveries made on the mountain, a few revolutionized our understanding of our place in the Universe. Here, for the first time, Harlow Shapley measured the size of the Milky Way Galaxy and located our position in it, far from the center. Then Edwin Hubble proved that the mysterious spiral nebulae, which astronomers had speculated about for decades, were in fact distant galaxies similar to our own. Then Hubble teamed up with Milton Humason and discovered that this immense Universe was expanding. Space itself was getting bigger. This finding, when run backwards in time, lead straight to the Big Bang Theory. So this is where modern cosmology began, and thus, in our long search for our origins, Mount Wilson holds a unique place in human history. Today, our original solar and nighttime telescopes, the world’s largest for two generations of astronomers, have been joined by the new CHARA array, which has the highest resolution of any optical or infrared system ever built, achieving unprecedented views of the stars.

Hubble guiding Mount Wilson's 100-inch Telescope in 1924, shortly after he proved the existence of distant galaxies. Photo: Carnegie/ Huntington Library. Photos at the top of the page: 1-Matt Adame, 2-MWO, 3-Steve Padilla. Photos below, left to right: I-MWO, 2-Dave Jurasevich, 3-MWO, 4-NGC 7331 by George Willis Ritchey.
Explore Mount Wilson in Person

Explore Mount Wilson in Person

Explore Mount Wilson On-Line

Explore Mount Wilson On-Line

Support Mount Wilson Observatory

Support Mount Wilson Observatory

  • Help keep the Observatory operations going and preserve its famous telescopes for future generations, Donate!
  • Join the people who keep the Observatory programs going, Volunteer.

George Ellery Hale, 1910. Photo: Carnegie/ Huntington Library

The Observatory’s founder, George Ellery Hale, built four telescopes, each one in succession becoming the largest in the world. Here they are shown to the same scale. His first was the 40-inch refractor at Yerkes  (in Wisconsin) on the left, but then he began building the more revolutionary–and more compact–reflector telescopes, using a large mirror instead of a lens. His next two are on Mount Wilson, the 60-inch and the 100-inch. (While not quite as grand as his last, these two had the light gathering power for astronomers to discover our place in the expanding Universe.) His fourth, the 200-inch Hale Telescope at Palomar, is represented on the right by one of Russell Porter’s famous cutaway drawings. This image has been reversed and extended on the left side for a better comparison of the relative sizes of the full domes. Hale’s telescopes were the biggest from 1897, when Yerkes opened, to 1993, when the Keck telescope in Hawaii was completed–a span of 96 years. To see these drawings enlarged, click here. Drawing credits: University of Chicago/Yerkes Observatory, Carnegie Observatories, Palomar Observatory/Caltech.

Public Ticket Nights for individuals returning this year!

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Mount Wilson Observatory
Mount Wilson ObservatoryWednesday, May 17th, 2017 at 11:19am

We have frequent inquiries regarding our hours of visitor access, so our staff produced this sign. We are only limited by the weather.

Mount Wilson Observatory
Mount Wilson ObservatoryMonday, May 8th, 2017 at 4:10pm

An overnight snowfall of 2.7 inches required the rescheduling of the concert today. It continued to snow today, so let's try again when it is warmer.

Sunday, May 14th, 2017 at 1:12pm
Jupiter and its moon Europa as seen through the 100-inch telescope. Picture taken with a #iphone7 held to the eyepiece. MtWilsonObs photo
Tuesday, March 7th, 2017 at 11:23am
Cold and clear evening up here tonight! Visit our tower cam on our website for live views of the 100-inch dome. MtWilsonObs photo
Tuesday, March 7th, 2017 at 11:21am
RT @rareflwr41: A special treat: @MtWilsonObs director (Thomas Meneghini) came to help us at our #Outreach event today @CarnegieAstro :-)!!… MtWilsonObs photo
Friday, March 3rd, 2017 at 2:18am
RT @AnotherBruce: Heading up to @MtWilsonObs this morning. Going to show some students the Best Observatory Ever.