A century ago, the tranquil air above Mt. Wilson was an astronomer's dream. Not yet polluted by light from the developing communities below, the 5,800-foot-high peak in the San Gabriel Mountains was ideal for observing the universe.
From the famed observatory that sits atop the pine-covered mountain, some of the greatest astronomical discoveries of the 20th century were made.
It is where Nobel laureate Albert Michelson determined the speed of light, Edwin Hubble proved that the universe was expanding, and where, 100 years ago last month, observatory founder George Ellery Hale discovered magnetic fields on the sun.
But as Los Angeles grew, the nighttime glow of urbanization drove astronomers to the darker skies of Hawaii, Arizona and Chile. Mount Wilson Observatory's scientific importance shrank.
By the mid-1980s, the mighty 100-inch telescope used by Hubble was gathering dust and the entire observatory was on the verge of becoming a relic of astronomy's past.
Today, Mount Wilson appears ready to again play a key role in ground-based astronomy. It has become a testing ground for newly perfected technology that allows astronomers to study neighboring stars despite the glare of city lights.
"It's almost a temple to astronomical history and current research," said Jack Harvey, an astronomer at the National Solar Observatory at Kitt Peak, Ariz.
The mountain's original scientists scaled its steep slopes for its unsurpassed "seeing" -- what astronomers call the clear views that result from the combination of dark skies and steady air. Ironically, the inversion layer that keeps smog trapped over Los Angeles is a blessing for stargazers because it reduces the atmospheric turbulence that causes stars to twinkle and blurs astronomical images.
Hale established the observatory in 1904 with backing from the Carnegie Institution for Science to test his theory that magnetic fields existed on the sun. Despite perfect sky conditions, his early efforts ran into a problem that Hale hadn't anticipated.
"The sun would heat the Earth enough that convection currents rising right from the ground itself would distort the image," said Edward Rhodes, a professor of astronomy at USC.
Hale's solution was to construct a 60-foot solar tower high enough to avoid interference from heat waves. Then, by comparing the spectrum of light from a sunspot to that of regular sunlight, he found the unmistakable signature of a magnetic field -- the first observed beyond Earth.
