Home Where We Discovered Our Place in the Universe Due to the Pandemic, Most Public Activities Have Been Suspended. For the Current Status of the Cosmic Café, Observatory Buildings and Grounds, Please Check the Homepage Below. VISIT US DONATE

Mount Wilson Observatory Status


Mount Wilson Observatory remains closed due to the pandemic. We hope to be able to reopen limited access soon as conditions improve. Stay tuned!

Due to the ongoing pandemic, ALL TOURS, EVENTS, AND TELESCOPE VIEWING have been suspended until further notice.

Due to the Bobcat fire, a large portion of the Angeles National Forest is CLOSED, including ALL trails to Mount Wilson.  For more information, please read the  U.S. Forest Service closure order.

Watch an extraordinary record of the Bobcat Fire here. It is a 360 degree, panoramic, time-lapse video of the fire as it started and eventually came up and around the Observatory. The video, “Bobcat Fire Time Lapse from Mt. Wilson 9/4/20-9/19/20” was created by Siobhán Dougall, who stitched together 10,500 images recorded by our four HPWREN tower cams.

To recover from the Bobcat Fire and the loss of revenue from the pandemic, Mount Wilson Observatory needs your help! If you can, please make a donation or join with a supporting membership. Our largely volunteer organization receives no regular support from any institutions or government, so any help we get from the public during this tough year is greatly appreciated!!!  Thanks for supporting science, education, and the preservation of this world-class historic site.

Attention Mount Wilson Observatory science history buffs and future Docents: Our Trustee, longtime Docent, and retired JPL astrophysicist, Tim Thompson has a recorded Zoom presentation available here.

One of  a series of online presentations from Palomar Observatory, Thompson’s 2/06/21 talk highlights many of the innovations and discoveries in astronomy made at Mount Wilson Observatory. In the 1 hour 47 minute lecture with slides, he goes into some depth, explaining the astrophysics behind some of the more important work done on the mountain, past and present. While many are familiar with Hubble and Shapley’s contributions to modern cosmology, there were many other less well known discoveries made here that changed the course of astronomy.


The December Issue of our Quarterly Newsletter, Reflections is Now Available Online.

Click here to read the December issue of our newsletter and get a quick update on our status during the pandemic and post-Botcat Fire era.

The feature article is on the fire, which lingered in the canyons below Mount Wilson right up until our first major storm put an end to it with a blanket of snow on the 27th and 28th of December. It burned for more than three months, after starting on Labor Day weekend. The second article is on Betelgeuse and Baade. Betelgeuse is the first star ever measured (other than the Sun), a remarkable achievement made at the Observatory 100 years ago this December. (To read the first article about this milestone in astronomy, see last December’s issue of Reflections here. The follow-up article on how Walter Adams, the second director of the Observatory, figured out how to measure distances to thousands of stars, a prerequisite to determining their sizes can be found here.) Betelgeuse, a red supergiant, is on the shortlist of “nearby” stars that are expected to go supernova in the next 100,000 years. Walter Baade, one of the Observatory’s more famous astronomers, observed his first supernova one hundred years ago from his native Germany. He and Fritz Zwicky at Mount Wilson brought supernova research into the modern era,

A letter from our Chairman of the Board of Trustees, Sam Hale, updates us on the Observatory’s status and progress in a difficult year.

We know that many of our supporters are struggling with the pandemic and economic downturn this year, so we are especially thankful to all who have helped us “weather the storm.” All who donated from July 1 to December 1 are honored in the newsletter. All these donations, large and small, have helped make up for some of our shortfall in revenue this year. Those who joined us as members are also deeply appreciated and are listed on our Website. We thank them all for supporting science, education, and the historic preservation of this remarkable Observatory high above Los Angeles–where we discovered our place in the Universe!

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, during WWI, Harlow Shapley measured the size of the Milky Way Galaxy for the first time and located our position in it, far from the center. Then, in 1924, 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 confirmed that this immense Universe was expanding. Space itself was getting bigger. This finding, when run backwards in time, led a few decades later to the Big Bang Theory. Mount Wilson is where modern observational cosmology began. It holds a unique place in humanity’s search for our most distant origins. 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.

A publicity photo of astronomer Edwin Hubble guiding Mount Wilson’s 100-inch Telescope in 1924, shortly after he proved the existence of distant galaxies. Photo: Carnegie Observatories/ Huntington Library.

If you are on the Observatory grounds, state law requires you to wear a mask or face covering. Please keep social distancing going on the trails and on the Observatory grounds. Covid-19 numbers are currently going up in Southern California. Thank you for your cooperation!


Subscribe to Mount Wilson Observatory News for updates on what is (or isn’t) happening on the mountain in 2020. Click here.

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

  • Become a Member of the 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.

Mount Wilson Observatory’s Membership Program

Join the Observatory  as a member! By doing so, you get a number of benefits and you help us renew this historic mountaintop, so that it may inspire well into the future. We aim to build a larger community to keep us moving forward with educational STEM programs, undergraduate research, public outreach, ongoing scientific research, and restoration of our 116-year-old observatory.

Please consider becoming a member in 2021, to help us through this year. If you can. Sign up for the individual membership, family membership, or a higher level, all named after one of our famous astronomers. Sign up is easy. Click here to go to our membership page.

What’s that Strange Light on Top of Mount Wilson?

Called Sunstar, it is an array of six prisms which take incoming sunlight and refract it, bending the light and spreading it into a spectrum–all the colors of the rainbow. It is mounted near the top of the Observatory’s 150-foot Solar Telescope Tower. With motion controls, it can be remotely directed to project the spectrum to a specific point in the Los Angeles basin. An observer below will see an intense point of light in a single wavelength, shining like a brilliant jewel from the ridgeline of Mount Wilson, 5800 feet above in the San Gabriel Mountains. The prisms can be moved to change the color of light an observer sees, or the observer can walk in one direction or another to change the color. In this case, the observer is actually walking across a giant spectrum some 250 yards long. While still very bright, at the great distances involved, it is perfectly safe to look at a single wavelength of sunlight. For more information and a schedule, go to our Sunstar page.

The centennial, paper architectural model of the 100-inch Telescope is now available to download for a small donation to Mount Wilson Observatory. Click here to go to the model page.

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.

To view our Facebook feed, please click here.


Friday, May 14th, 2021 at 12:59am
We are resurrecting the glass-plate camera on the 60" telescope. With some light oil, we were able to free the moving plate holder that had not been exercised since 1986. The first target to test this arrangement will be the moon next week. https://t.co/j8DgezGL6p MtWilsonObs photo
Thursday, May 13th, 2021 at 1:06pm
The 150' Solar Tower @ Mount Wilson is an overlooked but iconic facility at the Observatory. It's also one of the most visible structures on the mountain as viewed from the LA basin. It was constructed to study the position, strength, & polarity of magnetic fields and of the Sun. https://t.co/jMafdGt6jf MtWilsonObs photo
Friday, May 7th, 2021 at 4:45pm
While we are sorting out how to best open our public viewing program this season, we're taking this opportunity to visit our telescopes, piece-by-piece. We're starting with the 100" Hooker Telescope's base truss and its journey to the top of Mount Wilson. @MackTrucks https://t.co/wZOJmC4LUD MtWilsonObs photo