Be aware of winter conditions in the mountains before driving up. After winter storms, like the one on Dec 5-6, the upper roads may have lingering patches of black ice, which can contribute to an accident, and recently did. This is especially true on Red Box Road from the Angeles Crest Highway (2) up to the Observatory. This road is on the north side of the mountain and often receives little sun to melt the ice. Please drive it with caution.

Our popular Weekend Public Tours have ended for the year and will resume March 30, 2019. With advance notice, private tours are available all year, but may be cancelled due to weather conditions in the winter months. For more information on private tours clicker here. To schedule a private tour, send us an email at:

The Cosmic Café has closed for the season and will reopen on March 30, 2019. The grounds, museum, and 100-inch Telescope viewing gallery, however, will remain open every day of the year, except Christmas, and when snow and ice, or other hazardous conditions warrant a temporary closing. The gates will be open from 10:00 am to 4:00 pm during the winter season.

Telescope Sessions for the year have ended. We will not be taking reservations for 2019 until March 1st, 2019, when our reservation calendar will be reopened.

George Ellery Hale

Pioneering Astrophysicist

Founder of Mount Wilson Observatory


Mount Wilson Observatory’s New Membership Program

The Observatory is launching a membership program for those who would like to join us with ongoing support. 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 114-year-old campus.

We are just five years away from the centennial of Mount Wilson’s most well-known discovery, astronomer Edwin Hubble’s determination that all the faint “spiral nebulae” are really distant galaxies. We have many things we want to do to prepare for this grand event in 2023. Our goal is to bring the Observatory up to a more sustainable level by this time, so that we can properly showcase the incredible science accomplished on this spectacular mountain above Los Angeles.

As the 2018 draws to a close, please consider joining us with a membership to get the new program off to an amazing start. Sign up for the individual membership, family membership, or a higher level named after one of our famous astronomers. Sign up is easy. Click here to go to our new membership page.

We are a 501(c) non-profit, so your membership is tax-deductible. As always, end-of-year donations are also welcome, which are also quick and easy via our website or mail: Mount Wilson Insitute, P.O. Box 94146, Pasadena, CA 91109. Our largely volunteer organization receives no regular support from government or institutions.

End the year on a high note with an inaugural membership to Mount Wilson Observatory!

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, led straight to the Big Bang Theory. This is where modern cosmology began. 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


Sunstar is an art/science collaboration by Liliane Lijn and John Vallerga

A closeup of the Sunstar prism array, mounted near the top of the 150-foot Solar Telescope Tower.

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

During the last year or so we have been asked this question many times. We have been testing a special art installation called Sunstar, created and owned by artist Liliane Lijn and astrophysicist John Vallerga. It is on loan to Mount Wilson Observatory, and can now be seen from a number of locations around the area. For a schedule go to our Sunstar page.

An array of six prisms, Sunstar takes incoming sunlight and refracts 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.

Why are we doing this? For the wonder of it, the pure delight at seeing brilliant spectral colors derived directly from the Sun, the source of light that gives us life.

For the science of it. Mount Wilson Observatory was the first built specifically to do spectroscopy, to capture light from the Sun and other stars and spread it out into all its wavelengths, so that all the information it contains could be deciphered. And this art installation is useful in our STEM outreach program for local schools — it generates intrigue in the spectrum and teaches spectroscopy, a powerful tool used in almost all sciences and many industries. Students in an open area can walk through the entire spectrum.

Finally, Sunstar draws attention to Mount Wilson Observatory, and is a fitting way to celebrate our founder George Ellery Hale’s 150th anniversary. He was a solar astronomer, visionary, and institution builder, who influenced many aspects of the development of  Pasadena from the moment he selected Mount Wilson as the site for the Carnegie Institution’s Observatory.

Thank you to all who contributed to our first Triple Match!

We raised $78,000 to get started with our plans to build much needed public restroom facilities on the eastern side of the Observatory near the telescope domes. More funds will be needed to complete the project, as construction on the mountain, a mile above Los Angeles, is costly, but it is a fantastic start. When finished, it will greatly improve the experience of our many visitors, such as school groups, hikers, and others who enjoy the mountaintop. Currently, we often need to rent restroom facilities for our special events, which costs us more than $32,000 a year. The new restrooms will make the Observatory more financially sustainable in the long term by sparing us this annual expense.

Dear Friends & Supporters of Mount Wilson Observatory,

This spring, I decided to help the Observatory with a pledge of $20,000 on the condition that others donate an equal amount. It quickly evolved into a triple match, with a small group—trustees and others—pledging another $20,000. The response was overwhelming: by the deadline, on September 16, not only was the goal met, it was exceeded by more than $6,000!

We at the Observatory are filled with gratitude for those who gave so generously to make this first ever triple match a resounding success. I am so thrilled by the response, I will also match the extra $6,000. My deepest thanks to everyone, near and far, who pitched in!

Our mostly volunteer staff works very hard to maintain and preserve this world-class site both for its ongoing scientific research and its remarkable history. Your help is deeply appreciated by all of us. The love of the place is what keeps us going!

With Heartfelt Gratitude,

Mike Horner
Mount Wilson Trustee

Stephen Hawking, in front of the 150-foot Solar Telescope on one of his visits to Mount Wilson Observatory, June 2, 1990. Photo: Mount Wilson Observatory.

Stephen Hawking (1942-2018)

A giant of human intellect, Stephen Hawking greatly advanced our understanding of the Universe, from black holes to the Big Bang. He was born January 8, 1942, on the 300th anniversary of Galileo’s death, and passed away on March 14th, the anniversary of Einstein’s birth. On his visits to Caltech in Pasadena, he made the pilgrimage up to Mount Wilson (as Einstein did) on several occasions to see the observatory where Hale, Hubble, Humason, and others laid the foundations of modern cosmology, which became his life’s work. Here is a link to Caltech’s news of his passing.

Stephen Hawking’s entry in the visitors book at Mount Wilson, June 2, 1990. He signed with his thumbprint. Photo: David Cendejas/Mount Wilson Observatory


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.

Subscribe to Mount Wilson Observatory News for updates on 2018 concerts, lectures, public telescope nights, and other events. Click here.

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.

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Wednesday, November 28th, 2018 at 12:28pm
Pretty gorgeous sunset at @MtWilsonObs right now. Courtesy of @hpwren = High Performance Wireless Research and Education Network. MtWilsonObs photo
Wednesday, November 28th, 2018 at 8:17am
We are launching our new membership program for those who would like to join us with ongoing support. Info here:
Wednesday, November 21st, 2018 at 12:29pm
Born #onthisday in 1889, astronomer Edwin #Hubble made his most important discoveries right here in Pasadena. Working @MtWilsonObs in the 1920s, he discovered the #Andromeda galaxy at a time when the #MilkyWay was thought to be singular to the universe. MtWilsonObs photo
Monday, November 12th, 2018 at 1:48pm
A good number of our volunteer force here at Mount Wilson are military veterans. We have everything from WW2 to post 9/11 veterans. Thank you for answering our nations call and keeping us safe. Happy Veterans Day!! 🇺🇸🇺🇸 #VeteransDay2018