Dobson was well known in San Francisco as a spare, ebullient figure who would set up a battered telescope on the sidewalk, call out to passersby to “Come see Saturn!” or “Come see the Moon!” then whisper astronomical lore in their ears while they peered into the eyepiece. To the casual beneficiaries of his ministrations, he came off as an aging hippie with a ponytail, a ready spiel and a gaudily painted telescope so dinged-up that it looked as if it had been dragged behind a truck. But astronomical sophisticates came to recognize his telescopes as the carbines of a scientific revolution. Dobsonians employed the same simple design that Isaac Newton dreamed up when he wanted to study the great comet of 1680—a tube with a concave mirror at the bottom to gather starlight, and a small, flat, secondary mirror near the top to bounce the light out to an eyepiece on the side—but they were made from such inexpensive materials that you could build or buy a big Dobsonian for the cost of a small traditional reflector. You couldn’t buy a Dobsonian from John Dobson, though; he refused to profit from his innovation.
Observers armed with big Dobsonians didn’t have to content themselves with looking at planets and nearby nebulae: they could explore thousands of galaxies, invading deep-space precincts previously reserved for the professionals. Soon, the star parties where amateur astronomers congregate were dotted with Dobsonians that towered 20 feet and more into the darkness. Now, thanks to Dobson, the greatest physical risk to amateur observers became that of falling from a rickety ladder high in the dark while peering through a gigantic Dobsonian. I talked with one stargazer whose Dobsonian stood so tall that he had to use binoculars to see the display on his laptop computer from atop the 15-foot ladder required to reach the eyepiece, in order to tell where the telescope was pointing. He said he found it frightening to climb the ladder by day but forgot about the danger when observing by night. “About a third of the galaxies I see aren’t cataloged yet,” he mused.
Meanwhile the CCD had come along—the “charge-coupled device”—a light-sensitive chip that can record faint starlight much faster than could the photographic emulsions that CCDs soon began replacing. CCDs initially were expensive but their price fell steeply. Amateurs who attached CCDs to large Dobsonians found themselves in command of light-gathering capacities comparable to that of the 200-inch Hale telescope at Palomar in the pre-CCD era.
The sensitivity of CCDs did not in itself do much to close the gap separating amateur from professional astronomers— since the professionals had CCDs too—but the growing quantity of CCDs in amateur hands vastly increased the number of telescopes on Earth capable of probing deep space. It was as if the planet had suddenly grown thousands of new eyes, with which it became possible to monitor many more astronomical events than there were professionals enough to cover. And, because each light-sensitive dot (or “pixel”) on a CCD chip reports its individual value to the computer that displays the image it has captured, the stargazer using it has a quantitative digital record that can be employed to do photometry, as in measuring the changing brightness of variable stars.
Which brings us to the Internet. It used to be that an amateur who discovered a comet or an erupting star would dispatch a telegram to the Harvard College Observatory, from which a professional, if the finding checked out, sent postcards and telegrams to paying subscribers at observatories around the world. The Internet opened up alternative routes. Now an amateur who made a discovery—or thought he did— could send CCD images of it to other observers, anywhere in the world, in minutes. Global research networks sprang up, linking amateur and professional observers with a common interest in flare stars, comets, or asteroids. Professionals sometimes learned of new developments in the sky more quickly from amateur news than if they had waited for word through official channels, and so were able to study them more promptly.
If the growing number of telescopes out there gave the Earth new eyes, the Internet fashioned for it a set of optic nerves, through which flowed (along with reams of financial data, gigabytes of gossip and cornucopias of pornography) news and images of storms raging on Saturn and stars exploding in distant galaxies. Amateur superstars emerged, armed with the skills, tools and dedication to do what the eminent observational cosmologist Allan Sandage called “absolutely serious astronomical work.” Some chronicled the weather on Jupiter and Mars, producing planetary images that rivaled those of the professionals in quality and surpassed them in documenting long-term planetary phenomena. Others monitored variable stars useful in determining the distances of star clusters and galaxies.
Amateurs discovered comets and asteroids, contributing to the continuing effort to identify objects that may one day collide with the Earth and that, if they can be found early enough, might be deflected to prevent such a catastrophe. Amateur radio astronomers recorded the outcries of colliding galaxies, chronicled the ionized trails of meteors falling in day- time and listened for signals from alien civilizations.
The amateur approach had its limitations. Amateurs insufficiently tutored in the scientific literature sometimes acquired accurate data but did not know how to make sense of it. Those who sought to overcome their lack of expertise by collaborating with professionals sometimes complained that they wound up doing most of the work while their more prestigious partners got most of the credit. Others burned out, becoming so immersed in their hobby that they ran low on time, money, or enthusiasm and called it quits. But many amateurs enjoyed fruitful collaborations, and all were brought closer to the stars.
I met Stephen James O’Meara at the Winter Star Party, held annually alongside a sandy beach in West Summerland Key, Florida. Arriving after dark, I was greeted at the gate by Tippy D’Auria, the founder of the Winter Star Party, who led me through thickets of telescopes reared against the stars.
“Steve’s up there, drawing Jupiter through my telescope,” Tippy said, nodding toward the silhouette of a young man perched atop a stepladder at the eyepiece of a big Newtonian that was pointing into the southwest sky. Comfortable in my lawn chair, I listened to the elders talk—a mix of astronomical expertise and self-deprecatory wit, the antithesis of pomp—and watched