Bobcat fire threatens historic Mount Wilson Observatory

Firefighters are battling to hold back the 41,000-acre fire from reaching the famed California observatory.
By | Published: September 15, 2020 | Last updated on May 18, 2023
Mount Wilson Bobcat fire

The Bobcat fire and Mount Wilson Observatory, as seen from the east HPWren camera on September 15.

University of California San Diego/HPWren
On Monday, September 14, one of California’s numerous wildfires, the Bobcat fire, marched toward the Mount Wilson Observatory, which is located in the San Gabriel Mountains northeast of Los Angeles, California. With the fire climbing upslope toward Mount Wilson, the observatory was evacuated, leaving just a skeleton crew of four maintenance staff remaining to assist firefighters until they are likewise ordered to evacuate. As of September 15, the boundary around the observatory remains secure.   

“Our thoughts are with the firefighters who will defend the Observatory against the approaching blaze,” wrote Mt. Wilson Observatory Chariman Sam Hale, in a letter posted to the observatory’s Facebook page. “We cherish the historic telescopes on the mountain that revolutionized humanity’s understanding of the Cosmos and hope they will be safe.”

Mount Wilson Bobcat fire
The Bobcat fire and Mount Wilson Observatory, as seen from the south HPWren camera on September 14.
University of California San Diego/HPWren

Mount Wilson Observatory

The historic Mount Wilson Observatory is home to a well-known 60-inch telescope, which is now the world’s largest telescope entirely devoted to public viewing. But the site also holds the famous 100-inch Hooker telescope, which reigned as the world’s largest aperture telescope from 1917 to 1949. 

In 2009, a large fire threatened the observatory, which led Mount Wilson to better prepare for the California’s yearly wildfire season. In preparation for this year, they cut trees, installed new high-flow hydrants, and topped off the 530,000-gallon water reservoir, which supplies 33 hydrants across the site and is supported by an additional 270,000-gallon water tank just outside the main gate.

The still growing Bobcat fire — which now encompasses some 41,000 acres — began on Sunday, September 6 in the San Gabriel Mountains. But it has since moved west into the Santa Anita Canyon. According to the Angeles National Forest, only 3 percent of the fire is contained. The exact cause of the fire is still under investigation.

Nearly 900 firefighters, several water-dropping helicopters, and air tankers dumping fire retardant are all battling the flames.

California Wildfires

A smaller, yet similar wildfire threatened Mount Wilson Observatory in 2017. But this historic site is not the only observatory threatened by this season’s raging wildfires. 

On August 19, the University of California’s Lick Observatory atop Mount Hamilton east of San Jose, California, was spared from one of the largest wildfires in the state’s history. At more than 100 years old, Lick Observatory was saved due to the tireless work of numerous fire crews.

“Thanks to their tremendous efforts, the telescope domes did not burn,” Lick Observatory director Claire Max said in a statement.

Now, firefighters are continuing to put their lives on the line to ensure the same outcome for the historic Mount Wilson Observatory.