Sunday, July 22, 2012

Mt. Wilson's 60-Inch Telescope

Like many sci-fi fans, I've always been fascinated by space, astronomy, and telescopes. Last weekend I was lucky enough to spend the night looking through Mt. Wilson's 60-Inch Telescope, located in the Angeles National Forest, north of Pasadena, CA.

Special thanks to the Keith and Alex for making this possible! And thanks to Reggie for starting the ball in motion and helping put it all together. Also a huge thank you to Tom The Telescope Operator and Shelley Bonus, our Session Director. They both were extremely knowledgeable and helpful and had our group laughing and learning all night long. You can also catch Shelley speak at The Planetary Society's Planetfest 2012 in Pasadena. Planetfest is a two-day celebration of the Curiosity rover's landing on Mars.

Some of the amazing objects we looked at are: Mars, Saturn, Neptune, M5 globular cluster (I think it was M5 - whichever it was, it looked really cool,) Cat's Eye Nebula, Ring Nebula, and Blinking Planetary Nebula.) One of the things that really stands out in such a big telescope is the amazing color in the nebulae and the details in the globular clusters.

The 60-Inch Telescope at Mt. Wilson is the largest telescope in the world open for public viewing. The "60-Inch" part refers to the aperture, or how big the mirror is. To get an idea how special this is, consider that the average backyard amateur astronomy telescope probably has an aperture of 3 to 8 inches.

The Mt. Wilson 60-inch design is a bent-Cassegrain reflector with a 60-inch diameter primary mirror which weighs 1900 pounds. The focal length is 960 inches (80 feet, or 2438cm) with a focal ratio of f/16. It has two 4-inch diameter eyepieces of 100mm and 50mm focal lengths. Those are mighty big eyepieces!

The Mt. Wilson 60-Inch telescope is the brainchild of famous astronomer George Hale. The history of the 60-Inch is fascinating, and the scope used very cutting edge technology for its time. In 1907 it was the largest telescope mirror in the world. The base, polar axis, and fork of the mount weigh over 16 tons. The mount used an ingenious design which supported over 21 1/2 tons of the telescope by floating on 650 pounds of mercury.

The great San Francisco earthquake of 1906 caused a shipping delay of the telescope itself, and over 150 tons of material for the building and dome were pulled to the top of the mountain by mule teams. The new wonder of the astronomical world was finally operational in December of 1908. It was the first telescope to photograph stars in other galaxies. It also took photographs of Halley's comet in 1910. The 60-Inch became "one of the most successful and productive telescopes in history."

Here are some pics from the trip. Click the image to view full size:

Beautiful views on the way up to Mt. Wilson.
The 60-Inch dome.
The telescope at twilight.
Get ready for some amazing views!
Saturn, taken with the camera hand-held up to the eyepiece. It was hard to get a good shot, and it doesn't really do justice to what the actual view looked like.
I should have brought a tripod! A shaky, hand-held long exposure. After dark, all the lights inside the dome are red, to preserve night vision.
Now that's an eyepiece! I wish I had this in my backyard. Oh wait, it sort of already is ;)
Here's a little comparison of the Mt. Wilson 60-Inch and the 8-Inch reflector I used to have:

Mt. Wilson 60-Inch:
Aperture - 1524mm
Focal Length - 24,380mm
Focal Ratio - f/16
4-Inch Eyepieces
100mm Eyepiece Magnification = 244x
50mm Eyepiece Magnification = 487x

Dobsonian 8-Inch:
Aperture - 203mm
Focal Length - 1200mm
Focal Ratio - f/5.9
1.25-Inch Eyepieces
25mm Eyepiece Magnification = 48x
9mm Eyepiece Magnification = 133x
9mm + Barlow Magnification = 267x

Check out the original 1906 engineering drawing for more specs on the 60-Inch. Visit the Mt. Wilson website ( for more information about viewing through the 60-Inch Telescope.

Coming next week: The return of Weird Wednesday and a long overdue behind-the-scenes update on the making of Gold Rush - a paranormal feature film!

What's your telescope story? Have you had a chance to view through a super-duper scope? Or, maybe you have a fun backyard 'scope story to share. Comment below :)

1 comment:

  1. Great report of an observing session at Mount Wilson...
    The Mt Wilson reflector has following focal ratios: f/5.1 Newtonian, f/16 Cassegrain and f/30 Coudé. It was the first telescope design to have three foci and saw first light on 7 December 1908.
    Philip Corneille FRAS