Atop a 5,700 foot mountain overlooking most of Los Angeles lies a place most Angelenos have never been. Driving about 40 minutes up California Highway 2 – Angeles Crest Highway – from La Canada Flintridge into the heart of Angeles National Forest will bring visitors into a world seemingly incredibly distant from the city, and yet it is only a few miles away… and a mile up. Here white domes are interspersed among the pine trees, cedars, and yucca. The Los Angeles Basin is on one side; the higher mountains on the other. This is Mt. Wilson, a place used mostly for leisure today, but responsible for some of the most important astronomical discoveries of the 20th century.
Despite being just outside Los Angeles, the Mt. Wilson Observatory, and its assorted telescopes and instruments, has been responsible for some of the most important advances in astronomy. It seems almost counterintuitive that, given the bright lights of one of the largest metro areas in the world, and the air pollution notorious in Los Angeles, that this would be a suitable spot for such endeavors. However, the very inversion layer that keeps LA’s smog in the basin makes the air above the smog about the clearest in the world.
While this is mostly smoke from recent fires, you can see how we are above LA, with downtown just visible.
Telescopes have existed here since 1905, when the Snow Solar Telescope was completed. Two other solar telescopes followed – one at 60 feet above ground and the other at 150 – and the solar discoveries made here have continued to redefine what we understand about the sun. Signage gives some of the highlights. In 1917, from this spot, the sunspots were first mapped, along with the magnetic strength and polarity of each. (This process has continued on every clear day to the present.) In 1961, astronomers working here discovered that the gas along the sun’s equator rotates faster than that at the poles, and that this changes the polarity of sunspots. While these might seem mundane, we now know that sunspots are responsible for all sorts of space-based weather phenomena, affecting the ability of things like communication satellites to function, so the basis for tracking them – discovered here – has massive practical application.
The 150-foot solar telescope
In 1908, a 60-inch telescope was completed at Mt. Wilson, followed by a 100-inch instrument in 1917, which was the largest in the world until 1949. Using these massive scopes, scientists like Harlow Shapley and Edwin Hubble measured the size of the galaxy, discovered new galaxies, and even measured the rate of expansion of the universe. It is hard to overstate how important these discoveries are in the history of astronomy, as they are the basis for the Big Bang Theory and really everything we know about the universe outside our solar system. Today, the 60-inch telescope is no longer regularly operated, but it can be rented out for private parties for $1,000 for a half night or $1,700 for a full night for up to 25 people. (Yes, I’m considering this for my upcoming 40th birthday.)
The 60-inch telescope dome
Lest one think that 1917 was the last major installation here, in 2002, Georgia State University built the CHARA array. CHARA, the Center for High Angular Resolution Astronomy, is an array of six telescopes spaced out over the mountaintop. Together, the resolving power of the array is equal to a telescope with a diameter of 331 meters! In 2007, CHARA became the first array to capture an image of the surface of a main sequence star other than the sun.
A dome visible over the trees
In normal times, visitors to Mt. Wilson can peek inside some of the domes, tour a museum dedicated to early 20th century astronomy, and see curated visitors centers at a couple different points. However, with COVID-19 still raging as of this writing, today only the mountaintop itself is open to the public, with small displays outside most of the telescopes and, of course, the spectacular views of the LA Basin and the surrounding mountains. There are picnic tables for lunch, but no open restrooms – the closest is back at the intersection of Highway 2.
And this view!
Of course, one can also reach Mt. Wilson by foot, hiking from Sierra Madre on a steep 7+ mile long trail. I am not one who could survive a hike of that nature, so driving worked better for me. However, there are some excellent trails here that could make for out and back hikes if one were so inclined. Or, just spend part of a day surrounded by the mountains, trees, and some of the finest astronomical history anywhere on the planet.
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