Astronomy's New Stars
Thanks to new technology, backyard stargazers have traveled light-years of late to join professionals in mapping the heavens
- By Timothy Ferris
- Smithsonian magazine, September 2002, Subscribe
(Page 3 of 7)
The solar research conducted by the industrial engineer Robert McMath, at an observatory he built in the rear garden of his home in Detroit, so impressed astronomers that he was named to the National Academy of Sciences, served as president of the American Astronomical Society, a professional organization, and helped plan Kitt Peak National Observatory in Arizona, where the world’s largest solar telescope was named in his honor.
Why were the amateurs, having played such important roles in astronomy, eventually overshadowed by the professionals? Because astronomy, like all the sciences, is young—less than 400 years old, as a going concern—and somebody had to get it going. Its instigators could not very well hold degrees in fields that didn’t yet exist. Instead, they had to be either professionals in some related field, such as mathematics, or amateurs doing astronomy for the love of it. What counted was competence, not credentials.
Amateurs, however, were back on the playing field by about 1980. A century of professional research had greatly increased the range of observational astronomy, creating more places at the table than there were professionals to fill them. Meanwhile, the ranks of amateur astronomy had grown, too, along with the ability of the best amateurs to take on professional projects and also to pursue innovative research. “There will always remain a division of labor between professionals and amateurs,” wrote the historian of science John Lankford in 1988, but “it may be more difficult to tell the two groups apart in the future.”
The amateur astronomy revolution was incited by three technological innovations—the Dobsonian telescope, CCD light-sensing devices and the Internet. Dobsonians are reflecting telescopes constructed from cheap materials. They were invented by John Dobson, a populist proselytizer who championed the view that the worth of telescopes should be measured by the number of people who get to look through them.
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.
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