Mt. Wilson

General Information
Historical Timeline
Sources and Other Information

General Information

Mt. Wilson is a favorite place for hikers, perhaps the best-known and best-loved place in the San Gabriel Mountains to Angelenos, and a fabled place for astronomers and physicists world-wide.

Hikers think of Mt. Wilson as a old friend, one they know well from its status as the place with more trails than any other area in the San Gabriels. Five trails climb to its summit, two more climb to Eaton Saddle along Mt. Wilson's ridgecrest, and, even using the most strict definition of Mt. Wilson, ten additional trails are found along its flanks (see below). This number is almost doubled using a more natural definition of the Mt. Wilson complex as including San Gabriel Peak and all the trails below it as well, which includes ~16 additional trails!

Although Mt. Baldy is the highest peak in the San Gabriels, Mt. Wilson is the peak that is in the heart of Angelenos as the symbol of the mountains. Mt. Wilson plays an important role in the everyday life of Angelenos, as the home of the towering complex of the radio and television antennae for nearly every station in L.A. Since the average person watches a nearly unbelievable amount of TV per day, and it's well known how many hours commuters spend listening to the radio each day, the average Angeleno feels a warm glow for Mt. Wilson's part in entertaining them for hours daily.

At night, the lights associated with those antennae give a strange, but ultimately reassuring feeling, to Angelenos. To see lights one mile up in the sky is a constant source of amazement, albeit a bit disconcerting for newcomers. Angelenos may not be able to navigate by the stars at night, but we do know which direction is north when we can see those lights!

Those antennae give Mt. Wilson something no place else in the San Gabriels or any other peak surrounding the L.A. Basin has: instant identification from the average Angeleno. Being able to identify something gives a sense of ownership, friendship and pride in that something. Most people have no idea where San Gabriel Peak, Waterman Mountain, Mt. Baden-Powell are, for example, and only a vague idea which one Baldy is if there is no snow on it. But everyone knows Mt. Wilson.

Mt. Wilson is the most accessible peak by car in the L.A. area. It is just a one hour drive from many places in L.A. to the very top of the mountain. And what a charming drive it is! The curves of the Angeles Crest Highway are fun to drive (ask any motorcyclist you see on the road), and rare is the traffic jam found so often on the freeways below. And unlike the monotonous homogenous freeway landscape of car dealers, gas stations, and restaurants seen along the freeways, the landscape along the Crest Highway is green and refreshing, offering views not seen elsewhere. No wonder Mt. Wilson is enchanting to the automobile-loving population of L.A.!

On summer days, the eyes of Angelenos turn toward Mt. Wilson just to see if it is there. When Mt. Wilson can't be seen, we know that at minimum we will endure a hazy day of restricted visibility, and at worse one of our famous smog alerts, which happen less often every year thanks to the AQMD.

But oh! Those views when it is clear! A stunning contrast occurs on winter days after a storm passes, and on clear autumn days and nights, especially when the Santa Anas blow without kicking up dust. When Mt. Wilson sparkles in sharp clarity, Angelenos feel the urge to drive to its top to survey the majestic close-up view of the L.A. basin it alone offers so easily. The splendor of the sweep of L.A., literally from the mountains to the sea, is stunning by day, and enchanting and captivating by night.

On those cold wintry days after the rain ends in the basin, Angelenos look up and see snow on Mt. Wilson, drawing them like a magnet to play along its slopes. Even though Mt. Baldy is covered with snow more often, its remoteness and inaccessibility makes it a distant cousin except to the smaller number of Angelenos who live directly below its peak. Watching the procession of snow-covered vehicles returning from Mt. Wilson via the Crest Highway, it sometimes seems that the most common way that precipitation arrives in the L.A. Basin from Mt. Wilson is via the filled beds of pick-up trucks, and not from the streams which drain its flanks!

Many Angeleno non-hikers have been known to attempt to climb Mt. Wilson due to one or more of the above reasons.

Physicists and astronomers from around the world yearn to see Mt. Wilson, and many of them consider Mt. Wilson to be the top attraction in Southern California, along with Palomar Mountain, for excellent reasons. After all, in our age of easy jet travel, Disneyland is no longer unique, fabled beaches are found in many locations, movies are filmed around the world, and many people who are attracted to California have already moved here. But the scientific history of Mt. Wilson is found no place else.

Mt. Wilson was where a major part of 20th century astronomy began. For 40 years, Mt. Wilson ruled as the king of optical and solar astronomy. Visitors from around the world made pilgrimages to this holy site for heavenly research during this entire 40 years, and continue to do so today.

Not just one, but two stunning revelations that forever changed our world were made by Edwin Hubble using the 100" telescope. For almost 200 years, astronomers and philosophers debated whether nebulae such as the famous Messier Objects were Kant's island universes (galaxies like our own Milky Way Galaxy, but extremely far away), or whether the nebulae were parts of our own Milky Way Galaxy. The preponderance of evidence in fact argued for the latter interpretation. In 1923 and 1924, Hubble used the 100" to unequivocally prove that these nebulae were external galaxies. In what we now call the Andromeda Galaxy and a few others, Hubble discovered cepheid variables, a particular type of variable star known in our own Galaxy. But these cepheids were so faint that they had to be 70 times farther away than the farthest such stars in our own Galaxy! Humankind's universe suddenly was a lot larger.

Hubble followed that up with an even more stunning announcement in 1929 that the universe was expanding! The universe was no longer a static place. Everything in it was flying away from us. Hubble discovered that the recession velocity of a galaxy was directly proportional to its distance from us (the Hubble Law). Since the main justification of the Space Telescope was to more precisely quantify the proportionality constant in this law, in part by observing cepheids in yet more distant galaxies, what better name for it than the Hubble Space Telescope?

These discoveries together surpassed even the Copernican Revolution in transforming our view of our place in the Universe. And they were made right here on Mt. Wilson.

The solar and astronomical telescopes atop Mt. Wilson were the most productive in the world for 40 years. Many Angelenos think the astronomical telescopes are useless now due to the heavy light pollution, the flip side of that awesome nighttime glitter of lights. But that viewpoint isn't entirely correct. Although the telescopes can no longer be used to study very faint objects, Mt. Wilson is still a premier site for studying brighter objects due to the stillness of the atmosphere caused by our famous atmospheric inversions. Hence the astronomical telescopes continue to produce scientific results today. Indeed, Mt. Wilson is currently at the forefront of the next frontier in astronomy using interferometry, with new smaller telescopes currently being built on the mountaintop. And when the basin is socked in by low clouds, the dark skies return to Mt. Wilson, at least for a while.

In 1922-1927, Albert A. Michelson used Mt. Wilson to determine the speed of light more accurately than ever before. He did this by timing how long it took for a beam of light emitted at Mt. Wilson to return from a mirror at Lookout Mountain on the south ridge of Mt. Baldy. In order to compute the speed of light accurately, the distance between the two locations also had to be very accurately measured. The distance was measured by the U.S. Coast and Geodetic Survey by triangulation from a 40 km baseline in the L.A. Basin. This 22 mile distance between Mt. Wilson and Lookout Mountain was measured with an error of only 1/4", the most accurately surveyed distance in the world at the time.

Is it any wonder that Mt. Wilson stands alone as the best Treasure of the Sierra Madre1?

Historical Timeline

See Historical Timeline


Map: Mt. Wilson Region (where else?) The location is marked by MW near the right center of the map.

See also: USGS 7.5' x 7.5' Map: Mount Wilson (34° 13' 26" N, 118° 03' 37" W)

By Car: Northeast on Angeles Crest Highway, SR2, 14.3 miles from I-210 to Red Box. Right on the Mt. Wilson Road 2.3 miles to Eaton Saddle and 4.5 miles to the gate at Skyline Park.

By Trail:

The trails of Mt. Wilson are:

Season: All.


See Mt. Wilson Region Hikes

Sources and Other Information

1 Sierra Madre was a name used for the San Gabriels by the Spanish padres, as well as by the L.A. Times as late as 1886. The range in the 1948 movie Treasure of the Sierra Madre was in Mexico.

Go to Field Guide to the San Gabriel Mountains: Places

Copyright © 2000-2001 by Tom Chester and Jane Strong
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Updated 6 November 2001.