OPEN WEEKENDS- Mt Wilson
Mount Wilson Observatory is located on the summit of Mount Wilson above Pasadena at an altitude of 5715 feet. Mount Wilson Observatory is visible from much of the Los Angeles area. Free of charge, this is a must see experience.
Viewing through the 100-Inch Hooker Telescope
The world’s largest telescope from 1917 to 1949, the 100-inch Telescope forever changed our understanding of the scale and nature of our Universe and launched a revolution in astronomy that continues through today. This world-heritage class instrument, used by many of the greatest astronomers of the Twentieth Century, has only recently been made available for regular public viewing. It is the largest telescope in the world that you can rent! Imagine looking through the telescope used by astronomers Edwin Hubble and Milton Humason in the late 1920s to measure the expansion of the Universe.
The 60 inch Telescope
Mount Wilson Observatory’s 60-inch telescope was completed in 1908 by Observatory founder George Ellery Hale with funding from Andrew Carnegie. It was the world’s largest operational telescope until Hale went on to complete the Mt. Wilson 100-inch telescope in 1917. For a more detailed history of this revolutionary instrument, which became the model for all large observatory telescopes of the future, see the article “Building the 60-inch Telescope.” Among the many important discoveries from the 60-inch telescope was Harlow Shapley’s revelation in 1918 that the accepted view of the time, that our Sun was near the center of the Milky Way Galaxy, was wrong. Shapley used the light gathering power of the 60-inch to show that our solar system is instead half way out toward the edge of our Galaxy. The telescope was a workhorse instrument for astronomy for over half a century and used by astronomical luminaries such as Edwin Hubble, Walter Baade, and Allan Sandage to unravel the secrets of stars and galaxies. Now retired from active scientific service, the 60-inch and the 100-inch telescopes are the largest in the world made exclusively available to the public. With their large light-collecting mirrors and the exquisite skies over Mount Wilson, these historic telescopes provide an unrivaled and unique astronomical experience.
CHARA (Center for High Angular Resolution Astronomy)
Mount Wilson’s newest astronomical instruments are Georgia State University’s optical interferometric array of six telescopes. This facility, located here because of the exceptional seeing conditions, puts Mount Wilson back on the cutting edge of astrophysics. The full array was completed in 2004. Each telescope of the CHARA Array has a light-collecting mirror 1-meter in diameter. The telescopes are dispersed over the mountain to provide a two-dimensional layout that provides the resolving capability (but not the light collecting ability!) of a single telescope a fifth of a mile in diameter. Light from the individual telescopes is conveyed through vacuum tubes to a central Beam Synthesis Facility in which the six beams are combined together. When the paths of the individual beams are matched to an accuracy of less than one micron, after the light traverses distances of hundreds of meters, the Array then acts like a single coherent telescope for the purposes of achieving exceptionally high angular resolution. The Array is capable of resolving details as small as 200 micro-arcseconds, equivalent to the angular size of a nickel seen from a distance of 10,000 miles. In terms of the number and size of its individual telescopes, its ability to operate at visible and near infrared wavelengths, and its longest baselines of 330 meters, the CHARA Array is arguably the most powerful instrument of its kind in the world.
Science Objectives
The Array is applicable to problems in almost all areas of contemporary astronomy. It is particularly suited to stellar astrophysics where it will be used to measure the diameters, distances, masses, and luminosities of stars, as well as to image features such as spots and flares on their surfaces. Other projects range from detecting planetary systems, imaging stars in process of formation, and studies of bright transient phenomena like novae.
For more information on this amazing research facility and the science that is emerging from it, please go to the CHARA array homepage. There you can find a video, Sizing up the Stars, that explains how interferometry works.
Astronomical Museum
Also on the mountain, next to the 100-inch telescope, there is a new exhibit hall that displays Albert Michelson’s original interferometer, used to get the first measurement of stars other than our Sun. The exhibit hall reveals in detail how the light is combined in the new CHARA area.
Weekend Public Guided Tours
Docent-led walking tours of the observatory take place on Saturdays and Sundays through November 29. The two hour tours depart at 11:30 a.m. and 1:00 p.m. sharp from the Cosmic Cafe located above the large parking lot at the entrance to the Observatory. A special feature of these tours is entrance into both the 60-inch and 100-inch telescope domes, as well as the observing room of the 150-foot Solar Tower Telescope. On rare occasions, a telescope may be closed to the tour due to a special event or maintenance.
Purchasing Tickets
Tickets are $15 (adults) and $13 (ages 12 and under & 62 and older). Tour tickets are available for same-day purchase at the Cosmic Café, and rarely sell out. For each tour, 15 spots are available.
If you have a large group, we urge you to opt for a private tour instead. These can be arranged by sending an email request to tours@mtwilson.edu.
Children under age 6 are not permitted. The tours involve about a mile of walking and climbing some stairs. Please read the Health Notice in the information tab.
Private Group Tours
Private guided tours may be arranged by individuals or groups in advance. A modest per-person fee is charged. More information is available here. Please contact tours@mtwilson.edu for more details and a private tour request form. Private tours are held in the daytime only and do not include looking through a telescope.
The Cosmic Café Sandwich Shop
Come up the mountain for a wonderful lunch in an incomparable setting. Located in the Pavilion above the main parking lot, serves fresh-made sandwiches and other treats and souvenirs on Saturdays and Sundays through early November, from 10:00 a.m. to 5:00 p.m.
Free Self Guided Tours
If you are planning ahead and would like a nice guide of your visit, Print your own free brochure for a self-guided tour and map of Mount Wilson.
An Interactive Map
To explore the telescopes and other sites on observatory online, click on the interactive map of the Observatory, above.
A 13-page Visitors Guide is also available for purchase at the Cosmic Café. Written by Hal McAlister, the second director of the Mount Wilson Institute and founder of CHARA, it is a well-illustrated guide to all the points of interest on the mountaintop.
Elevation Warning
The high elevation of the Observatory (5715 ft) and the change in elevation during the approximately one-mile and two-hour long tour are unsuitable for individuals with respiratory and heart problems or with limited mobility.
The century-old facilities are not ADA-compliant and, except for the Astronomical Museum and the Cosmic Cafe, offer no access to those who cannot climb multiple flights of stars. Thus, tours of the Observatory, either guided or unguided, are inappropriate for some elderly people and for those who are not in good health.
Visitors should take these factors into consideration before touring the Observatory.
A U.S. Forest Service Adventure Pass is required to park at the Observatory, as it is located on U.S. Forest Service land. A day pass may be purchased at the Cosmic Cafe (when it is open from April 4 to November 29 in 2020) on weekends between 9:00 a.m. and 5:00 p.m. Other times, the $5 day pass or the $30 dollar annual pass may be purchased at many locations around Los Angeles before you head up. Click here to go to the U.S. Forest Service website for more information about the Adventure Pass and where to buy them. Their website has a place to enter your location to search for nearby vendors. The Shell station in La Canada at the bottom of the Angeles Crest Highway should be selling them as well.
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Hours
April 1 – November 1 Saturday – Sunday: 10:00am – 5:00pm
December 1 – March 31 Saturday – Sunday: : 10am – 4:00pm
For additional information, visit the website @
www.mtwilson.edu/
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