The Fight to Save Mt. Wilson

Photo/David Cendejas

On September 6, a wildfire began deep in the San Gabriel Mountains. Dubbed the Bobcat fire, it quickly grew and began to threaten several of the foothill communities near Pasadena; it also began to move westward into Santa Anita Canyon, heading rapidly up the slopes toward the Mount Wilson Observatory, the home of modern observational cosmology and the site of some of the world’s most significant astronomical discoveries, including evidence for the expansion of the universe and the first evidence of dark matter. Also located within the perimeter of the observatory is the Caltech-operated Mount Wilson Seismic Station, one of the first six seismic stations installed in Southern California in the 1920s. Data from this seismic station have been used to locate and determine the magnitudes of earthquakes for the past 100 years.

The historic mountaintop site was evacuated on September 7, and the staff, from a safe distance, watched the approaching flames (captured by the observatory’s webcam) and took to social media to share updates and extend their gratitude to the firefighters.

One of those anxious observers was Sam Hale, chairman of the board of trustees of the Mount Wilson Institute and grandson of George Ellery Hale, the astronomer who founded the observatory in 1904 and was one of Caltech’s founders. In a note to supporters of the observatory on September 15, Sam Hale pointed out that personnel had been preparing all year for a fire, “as we do every year.” He continued:

“Trees have been cut. New high-flow hydrants have just been installed a few months ago to help replenish the fire department’s tanker trucks with water. ... Our giant 530,000-gallon reservoir has just been topped off and is ready to supply 33 hydrants across the observatory. ... Another 270,000-gallon tank, belonging to the U.S. Forest Service and maintained by the observatory, lies just outside our main gate to help defend the observatory and the broadcast towers, which provide radio, television, and communications to most of the LA Basin.

“As we go to battle, a skeleton crew of four of our maintenance staff will be on hand to assist the firefighters until such time as they are ordered to leave. They have been working all week in extremely smoky conditions readying hoses on all the hydrants, lowering metal shutters on building windows, and countless other critical fire-safety preparations. …

“While we hope the observatory makes it through relatively unscathed, the battle could go either way. ... We cherish the historic telescopes on the mountain that revolutionized humanity’s understanding of the cosmos and hope they will be safe. That is the most important thing.”

The firefighters were successful in pushing back that initial threat to the observatory. As of press time, Mount Wilson was still safe.

Watch webcam footage of the fire’s approach at mtwilson.edu.