Mt. Wilson Observatory telescope turns 100

When it gathered its first light on 1 November, 1917 at the Mt. Wilson Observatory, near Los Ageles, CA, the 100-inch Hooker telescope claimed the "world's largest" title from its 60-inch sister and held the No. 1 position for the next 31 years.

Using photographs he took with this telescope, Edwin Hubble demonstrated that the objects his contemporaries called "spiral nebulae" were actually huge systems of stars -- spiral galaxies, similar to our own Milky Way galaxy, but incredibly distant. Through this telescope, Hubble later confirmed that the universe is continuing to expand.

The telescope was built by the observatory's founder, George Ellery Hale and named after businessman John D. Hooker, who financed its construction.

In the 1920s, pictures from the Hooker Telescope on Mt. Wilson fundamentally changed our understanding of the cosmos. Credit: NASA/Mount Wilson Observatory

"In some ways, I consider Mt. Wilson Observatory to be the most important optical observatory in the history of astronomy," said UC Berkeley astronomer Alex Filippenko in an interview with the Los Angeles Times. Filippenko helped determine that the universe's expansion is accelerating, driven by the existence of a mysterious force called dark energy.

"[The telescope] was really an amazing instrument to use," added Filippenko, who as a Caltech graduate student was one of the last researchers to publish papers based on work conducted at the observatory.

Mount Wilson Observatory complex. Credit:NASA

To celebrate one hundred years of exploring the universe at Mt. Wilson Observatory, SPIE has made seven historical articles in the SPIE Digital Library open access for the month of November.

Articles from SPIE Classics offer a look at the Mt. Wilson Observatory and adaptive optics.

Adaptive optics upgrade for the CHARA Array interferometer
An on-telescope system that compensates for atmospheric turbulence will improve the telescope sensitivity, expand the target pool, and allow the study of young stars.

An adaptively corrected composite material telescope
Meter-class, composite astronomical telescopes are lightweight and, with adaptive optics, provide high-fidelity wave fronts and images.

Adaptive optics enhances power of astronomical telescopes
Advances in correcting image blur caused by low-altitude turbulence produce sharper images and wider fields of view with the world's largest telescopes.

New adaptive-optics technology for ground-based astronomical telescopes
An optical system that uses a miniature deformable mirror counters the effects of air turbulence to provide excellent resolution for imaging distant astronomical objects.

Holographic adaptive-optics system removes speed barriers
A new sensing technique takes away the need for computers in adaptive optics.

Progress in adaptive optics
New astronomical techniques promise a wide field correction of atmospheric degradation on ground-based optical and near-infrared telescopes.

Video: New vistas in Adaptive Optics
From the domain of large telescopes and military applications, adaptive optics technology is poised to spread to new applications.

For more information about current and future telescope projects, see what's happening at the 2018 SPIE Astronomical Telescopes + Instrumentation symposium.