John Dobson leads a group of amateur astronomers in discussion and gives points on how to make their own telescopes, called Dobsonian telescopes, on Feb. 13, 1999. (Con Keyes/The Los Angeles Times)

John Dobson, a former Hindu monk and a self-taught stargazer who developed a powerful, inexpensive telescope that almost anyone could build and became one of amateur astronomy’s most influential evangelists, died Jan. 15 at a hospital in Burbank, Calif. He was 98.

The death was confirmed by Bob Alborzian, coordinator of the Burbank chapter of Sidewalk Astronomers, an international organization that Mr. Dobson helped found in 1968. Mr. Dobson had a stroke a few years ago.

Called the “Johnny Appleseed of amateur astronomy,” the lanky, ponytailed Mr. Dobson started building telescopes in the 1950s as a monk at the Vedanta Monastery in San Francisco. His passion for the hobby led to his expulsion, freeing him to become a roving ambassador for the simple joys of studying the night sky.

“He created a hobby and a type of telescope that ensured that people could build their own and look farther across the universe than was possible for most people before his time,” said Anthony Cook, astronomical observer at Griffith Observatory in Los Angeles.

Mr. Dobson used cheap or salvaged materials such as glass from ship portholes and cardboard tubing to make his telescopes, the most radical feature of which is a simple, sturdy and highly effective wooden mount that allows users to easily point the scope at any spot in the sky. Over five decades, he taught thousands of people how to build one.

His design was eventually embraced by commercial manufacturers, who advertise the telescopes as “Dobsonians.” They remain “one of the most popular telescopes on the market,” said Dennis di Cicco, senior editor of Sky & Telescope magazine.

Dobsonian telescopes have made important contributions to astronomy, including the discovery in 1995 of Comet Hale-Bopp, the most-distant comet ever discovered by amateurs. One of its namesakes, Tom Bopp, was using a Dobsonian.

Alborzian, who had known Mr. Dobson since 1968, said he once urged Mr. Dobson to patent his design. He refused. “He said, ‘These are gifts to humanity,’ ” Alborzian recalled. “His goal was to open astronomy to the common man.”

Mr. Dobson had his critics. He did not, for instance, subscribe to the Big Bang theory but favored the idea of a “steady-state” universe with no beginning and no end. “I’m not interested in just the stars,” he told the Los Angeles Times in 2005. “I’m interested in the whole ball of wax.”

Although the steady-state theory has been widely discredited, Mr. Dobson was an unwavering supporter, which caused many in the astronomy establishment to dismiss him.

“He was unconventional,” di Cicco said.

John Lowry Dobson was born Sept. 14, 1915, in Beijing. His mother was a musician, and his father taught zoology at Peking University. Nervous about political unrest in China, his family moved to San Francisco in 1927. He received a degree in chemistry from the University of California at Berkeley in 1943 and went to work in the defense field.

In 1944, he joined the Vedanta Monastery in San Francisco, and he was asked to reconcile the order’s teachings with science. That assignment led him to build his first telescope, in 1956. He scavenged materials, including a 12-inch piece of porthole glass that he sanded into a telescope mirror.

When he was done, he peered at the moon and was profoundly moved. “Everybody’s got to see this,” he said.

Transferred in 1958 to the order’s Sacramento monastery, Mr. Dobson began building telescopes in earnest. Soon he took to smuggling parts into the monastery in fertilizer boxes after his superiors told him that his activities were inappropriate for a monk.

He was often away from the monastery to help others build their own scopes. That is what the other monks thought he was doing when they decided to expel him in 1967.

Mr. Dobson hitchhiked to San Francisco, where he began teaching and setting up his telescopes on street corners. He enticed passersby to look into the heavens. “Come see the sun!” he shouted, sometimes while twirling a lariat.

Brusque and witty, he explained the cosmos in easily understood terms. “If the sun were the size of a basketball,” he often said, “Jupiter would be the size of a grape, and the Earth would be the size of a very small grape seed.”

In 1968, he formed the San Francisco Sidewalk Astronomers with Bruce Sams and Jeffrey Roloff, who had built telescopes under his tutelage. Soon, he was barnstorming the country, setting up his telescopes in shopping center parking lots and national parks — anyplace, he said, “where dark skies and the public collide.”

With chapters across the country and abroad, Sidewalk Astronomers now has more than 10,000 members, director Donna Smith said.

In 1978, Mr. Dobson was invited to give a series of lectures at the Vedanta Society of Southern California and began to spend part of each year in Los Angeles. He lived at the Vedanta center in the Hollywood Hills, often hiking to Griffith Observatory, where he led public events such as a 12-hour telescope-building marathon in the mid-1980s.

His life was chronicled in films, including the 2005 documentary “A Sidewalk Astronomer,” directed by Jeffrey Fox Jacobs.

Survivors include a son, Loren Dobson of Sacramento.

In his 90s, Mr. Dobson was still a gypsy proselytizer for astronomy, lecturing and giving workshops as far away as Russia and China. Used to the most Spartan accommodations, he was known to sleep inside a telescope’s cylindrical tubes when he was on the road.

“There’s one thing nice about sleeping in a telescope,” he told the Ventura County Star in 2007. “You can’t roll out of bed.”