The dome containing Mt. Wilson’s 60-inch Hale telescope. Credit: Pauline Acalin
On August 20th, fifteen members from the Orange County Astronomers (OCA) club, myself included, gathered outside the steel dome of the 60-inch Hale reflector for a night of cosmic sightseeing. Mt. Wilson Observatory is located just outside Pasadena in the San Gabriel Mountains of Los Angeles County, CA.
If you ever have the opportunity to spend an evening gazing through a considerably large telescope, do not hesitate to sign up. In fact, why wait? Just get a group of friends together and rent a night with one of Mt. Wilson’s two giant telescopes.
Climbing to the top for the best views. Credit: Pauline Acalin
At sunset, our session director led us into the massive structure, up two flights of stairs and into a red-lit room containing the optical behemoth known as the 60-inch Hale telescope. Nearby is Mount Wilson’s other famous telescope, the 100-inch Hooker telescope. The Hooker telescope was the world’s largest until 1949 when the 200-inch (also named) Hale first saw light at the Palomar Observatory in California.
It should be noted that over the years I’ve grown fond of my 3.5-inch telescope. Countless photons have passed through its eyepiece, displaying glimpses of the universe to many a spectator. During its inaugural night under the stars, my little refractor granted me visual access to the captivating rings of Saturn for the very first time. What seemed like an apparition ignited an emotional sense of awe I will never forget. With this embedded memory, I was thrilled to learn that Saturn was the first target object for our group. Coordinates were sent to the scope, and its grand slewing maneuvers began as our group waited around the perimeter of the observation deck.
A stacked composite of Saturn using video captured through 3.5-inch Celestron telescope (left), and Mt. Wilson’s 60-inch Hale telescope (right). Credit: Pauline Acalin
My turn finally came, and it was magnificent.
The resounding creaks of the impressive rotating dome were oddly soothing as the open patch of night sky slowly relocated to the front of the telescope. Once the motion stopped, the sound of chirping crickets once again filled the dome.
We watched as our guide demonstrated the safest way to get your eye to the eyepiece. Due to the low position of Saturn, this strategy involved climbing a rolling stepladder, swinging your right leg over a rail, and lunging onto the telescope while keeping your left hand on another rail to stabilize yourself enough to safely bend forward to take a look. No big deal, especially for such a prized view.
My turn finally came, and it was magnificent. The planet was remarkably large, and its Cassini Division was plainly visible.
I wanted to capture an image of Saturn to compare with the one I had taken using my 3.5-inch refractor. Using my iPhone 6, I grabbed 35 seconds of video with the intention of later consolidating the best frames into a more representative “pretty” image of the planet, a technique known to planetary photographers as “stacking.” As you can see in the image, the difference in size is staggering.
For most of the night, the waxing gibbous moon was overhead–not the best conditions for viewing faint nebulae and galaxies. Nonetheless, over the course of six hours, we were each able to take our time viewing an impressive list of celestial objects including Campbell’s Hydrogen Star, Messier 13 (Hercules Star Cluster), Cat’s Eye Nebula, Ring Nebula, Blinking Planetary Nebula, Saturn Nebula, and Neptune. Most of these were striking in their brilliance and clarity, such as Albirio (the binary star) and Epsilon Lyrae (the famous Double Double star). All, for the record, were more vibrant in color viewed with Hale than with any telescope I’ve ever used.
The moon as seen through the 60-inch telescope. This photo is cropped to show the terminator (where the sunlit and shadow areas meet) of the waxing gibbous moon the night of August 20-21. Credit: Pauline Acalin
Light pollution has become a major issue since the construction of the observatory in the early 1900s. At the time, the Mt. Wilson site was chosen for its exceptional seeing conditions, attributed to its 5,700-foot summit, dark skies, and steady airflow. But as the population of Los Angeles continued to grow, so did its light pollution, preventing scientists from using the telescopes for effective observing.
As our night came to a conclusion at around 1:00 am, our guide had an unexpected treat for us. Although we were not able to look through the 100-inch telescope, our group was granted access to the dome.
Upon entering this legendary dome, our group let out a collective gasp. We agreed there were no words to properly describe the sheer magnificence surrounding us, from the giant apparatus towering above, to the artifacts tucked away in drawers and scattered about the room.
The dome rotates, keeping a swath of sky in line with the object the telescope is observing. Credit: Pauline Acalin
We were shown original blueprints for the construction of the telescope. Nearby, an old wooden workbench stood with an array of antique tools hanging neatly on the wall behind. And although we didn’t see it, perhaps best of all was learning of a storage locker in the basement, which reads “Hubble” across the front.
In the 1920s, Edwin Hubble used the 100-inch reflector to prove that the “spiral nebulae,” thought to be located within our Milky Way galaxy, were actually separate “island universes.” Hubble and Milton Humason worked together observing several hundred of these galaxies and determined that their radial velocity was directly related to their distance (known as Hubble’s Law), thereby discovering that the universe was expanding. In 2012, when the 100-inch officially retired as an instrument used for research, the observatory director decided to re-purpose the scope for the Public Access Program, which had already successfully inducted the 60-inch. The decision would also provide the Mt. Wilson Institute with additional income to continue maintaining this revered observatory.
Construction plans for Mt. Wilson’s 100-inch Hooker Telescope Credit: Pauline Acalin
Groups can rent an evening at either scope by making a reservation on the observatory’s website. Think of what a memorable class field trip this would make for a group of students. The 60-inch can accommodate up to 25 people for a fee of $950 per half night, and for the 100-inch, up to 18 people at $2,700 per half night.
While the cost may appear pricey, once divided among the group the fee is quite a bargain. For a night of viewing the cosmos at an observatory responsible for changing the way we look at the universe, the experience is worth its weight in gold. I can’t wait to return with another group!