Unexpected History: John Dobson’s Tumbleweed Reflector

Yesterday evening, my family and I attended an astronomy event put on by the Astronomical Society of Kansas City called ‘Three Dots of Light in the Sky’ at the Lexington Battlefield State Historic site. While there was no new information or views for an amateur astronomer with 43 years experience like me, it was still quite fun to see kids and adults in attendance react to their first clear view of Saturn’s rings, Jupiter and his Galilean moons, Mars’ bold red disc, and Venus’ quarter phase. No slides inserted in the telescopes or professional photographs installed in the tops of the surrounding trees. This was their Solar System – up close and personal. It was also very cool to see other newer and better telescopes than my humble 3.5-inch Newtonian and small Meade refractor.

It was also fun to revisit the spot where we viewed last year’s total solar eclipse – almost exactly a year ago, when the clouds parted long enough on either side of totality for us to have an unforgettable view.

On the far end of the field was a handmade 10-inch Newtonian reflector on a Dobsonian mount. As I milled around looking through the other telescopes in the fading light and heard fragments of conversations, I heard the lady tending the reflector say it was built for only a few hundred bucks. Then she said something that stopped me in my tracks – this telescope was built by John Dobson.

“John Dobson?”

“Yes, John Dobson.”

The John Dobson!?”

“Yes, the John Dobson!

“The Sidewalk Astronomer!?”

“Oh, you’ve heard of him?”

“Uh, you could say that!”

Of course, since my historical and appraisal work has brought me face to face with many significant historical artifacts over the years, I’m not easily startled. So, when my jaw drops and my hand involuntarily goes to my head in shock like it did, I bloody well mean it.

Okay, what’s the big deal? Admittedly, to anyone outside the astronomy community, it’s won’t seem like one. But to an astronomer with a deep sense of history, it was.

John L. Dobson (1915-2014) was an amateur astronomer, best known for inventing a low-cost and portable Newtonian reflector telescope style that has become known as the Dobsonian.

A Vedantan monk in the 1960s, he was tossed out of his California monastery where he was working to reconcile astronomy with the teachings of Vedanta over a sad misunderstanding connected to his telescope building and public observing sessions. Fortunately for amateur astronomy, he was then able to devote himself to his greatest passion – sharing his love for astronomy with the public.

Dobson would go on to appear twice on The Tonight Show with Johnny Carson and be featured in the PBS series The Astronomers (1991).

Because telescopes of the time were often mounted with astrophotography in mind, they could be a bit inconvenient in a public setting where people expect to quickly look in an eyepiece and see something fantastic. A few of you will know this if I’ve ever given you a telescopic tour of the night sky with one of my telescopes which have unmotorized equatorial mounts. Speed and ease of use are vital in the public sphere.

Dobson borrowed ideas from mountings used by artillery and invented a new mount for ‘light bucket’ Newtonian reflectors that was fast, smooth and very easy to use. Fundamentally a caring and gentle man, his nature meant he was uncomfortable with his name being attached to what he considered to be a basic idea of a convenient altazimuth mount. But the attribution is well deserved in my humble opinion.

One of the telescopes he built with his unique mount was called Tumbleweed. He put it together for about $300, and used a ship’s 10-inch portal glass for the mirror blank, grinding and coating it himself. The telescope would become one of his main instruments during his popular sidewalk astronomy lectures around the country, as the image linked above shows.

This was the telescope on display. Refurbished a bit, but still the same telescope.

Last night, like it must have countless others over the last several decades, it took me to Saturn. Such special moment for this astronomer and historian.


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