The long-lived master of sidewalk astronomy died peacefully on January 15th. Emerging from obscurity in 1968, he introduced simple ideas that revolutionized how amateurs make and use large reflecting telescopes.

A simple notice appeared yesterday on the website of the San Francisco Sidewalk Astronomers: "It is with heavy hearts that we must report the passing of John Dobson. He died peacefully this morning, Wednesday, January 15th, in Burbank, California. He was 98 years old. He leaves behind a son, numerous close friends, and fans and admirers worldwide."

Ever since emerging from obscurity in 1968, when he left his order of Vedantan monks and founded the SFSA with students Bruce Sams and Jeff Roloff, Dobson has been a force of nature in amateur astronomy. He'll be remembered most for his novel approaches to making low-cost, large-aperture reflectors. The key was a simple, alt-azimuth wooden mount that anyone could build. Today millions of stargazers worldwide use these Dobsonian telescopes to sweep the nighttime sky.

Dobson was a barnstorming evangelist for the simple joys of stargazing. During the 1980s and 1990s he traveled widely to talk about his two passions: introducing people to the night sky and pondering the complexities of the universe. As time passed, he became more focused on the latter, proffering a framework for cosmology that flew in the face of conventional thinking. (Here's a 6½-minute-long sample of that.)

Bob Naeye, S&T's editor in chief, got to know Dobson when he lived in San Francisco a decade ago. "I remember a number of occasions of doing sidewalk astronomy where John Dobson, Jane Houston-Jones, Morris 'Mojo' Jones, and I would each be at one of the four corners at a busy intersection. Our favorite spots were 9th and Irving, and 24th and Noe. When I was in the area a few months ago, I made a point of visiting those two intersections to bring back fond memories."

Dobson had slowed in recent years, not straying far from his home base in Southern California. In August 2005, at the annual Stellafane convention in Vermont, hundreds of fans feted Dobson as he turned 90 (a little early: his birthday was September 14th). I offered extended "Happy Birthday" wishes when he celebrated his 95th in 2010.

The Sidewalk Astronomers (as they're now called) have a detailed biography of Dobson, and to mark his 80th birthday longtime acquaintance David Levy wrote a gracious profile that appeared in Sky & Telescope's September 1995 issue.

This year's International Sidewalk Astronomy Night, planned for March 8th, will be dedicated to Dobson's memory.

We all knew that John Dobson wouldn't be with us forever. Curiously, just a few days ago, I wondered how he was doing. I should have made that call to find out and wish him well.