Timothy Ferris is a serious amateur astronomer. He spends a substantial amount of his time and money roaming around at night among planets and stars and galaxies. He owns a place called Rocky Hill Observatory in California where he can stargaze to his heart’s content through telescopes of modest size and excellent quality. He belongs to the international community of observers who are linked by the Internet as well as by the shared sky in which they are at home. Serious amateur astronomers, unless they are retired or independently wealthy, must have a day job to support their nocturnal addiction. Ferris has a day job as a writer of books explaining science to the general public. He has written many books which are widely read and have effectively reduced the level of scientific illiteracy of the American population.

This book is similar to the others in some respects and different in others. Like his previous books, it is factually accurate, it contains a wealth of information about the universe we live in, and it makes the information easily digestible by seasoning it with good stories. Unlike his other books, it is a love story, describing how Ferris fell in love with astronomy at the age of nine and how this passion has enriched his life ever since. But he does not write much about himself. The book is mainly a portrait gallery of the diverse and colorful characters who have shared his passion, with a description of the contributions that they have made to the science of astronomy.

Ferris has sought out his amateur astronomical colleagues, visited them in their homes and observatories, listened to their life stories, and watched them at work. One of these colleagues is Patrick Moore, who has also supported himself by writing popular science books in the daytime while exploring the sky at night. Ferris visited him in the English village of Selsey where he lives and works. Many years ago, before any human beings or human instruments had surveyed the back side of the moon from space, Moore was observing the moon systematically with his small telescope at Selsey.

The moon normally keeps a fixed orientation as it revolves around the Earth, so that only the front side is visible. But it wobbles slightly in its orbit, so that occasionally some regions that are normally invisible can be seen at the edge of the visible face, extremely foreshortened and inconspicuous. Moore was studying these normally invisible regions at a moment when the moon’s wobble was at a maximum, and discovered Mare Orientale, the biggest and most beautiful impact crater on the moon. Moore gave it the name Mare Orientale, Eastern Sea, because it is hidden behind the eastern edge of the moon and because it is a dark circular region similar to the dark regions on the front side of the moon which the amateur astronomer Johannes Hevelius called seas when he mapped them in 1647.

Hevelius was a brewer in Danzig who made the first accurate map of the moon. Even at times of maximum wobble, only a small part of Mare Orientale can be seen from the Earth. Only an observer with long experience and deep knowledge of lunar topography could have recognized it in the fragmentary view of the moon’s edge that Moore could see from Selsey. Professional astronomers do not have such experience or such knowledge. Only an amateur could have discovered Mare Orientale, because only an amateur has the time and the motivation to study a single region of the moon with single-minded dedication.

Patrick Moore is one of many examples illustrating the main theme of Ferris’s book. The theme is the importance of amateurs in the exploration of the universe, not only in past centuries but also today. Patrick Moore was an old-fashioned amateur when he discovered Mare Orientale, observing the moon laboriously with his eye at the telescope, drawing maps of his observations with pencil and paper. Amateurs today observe the sky with digital electronic cameras, recording the images with personal computers using commercial software. The role of amateurs has become more important in the last twenty years, because of the advent of cheap mass-produced electronic cameras, computers, and software. Serious amateurs today can afford to own equipment that few professional observatories could afford twenty years ago. Personal computers are used not only to record data but to communicate rapidly with other observers and to coordinate observations all over the world.

There are many areas of research that only professional astronomers can pursue, studying faint objects far away in the depths of space, using large telescopes that cost hundreds of millions of dollars to build and operate. Only professionals can reach halfway back to the beginning of time, to explore the early universe as it was when galaxies were young and the oldest stars were being born. Only professionals have access to telescopes in space that can detect the X-rays emitted by matter heated to extreme temperatures as it falls into black holes.


But there are other areas of research in which a network of well-equipped and well-coordinated amateurs can do at least as well as the professionals. Amateurs have two great advantages, the ability to survey large areas of sky repeatedly and the ability to sustain observations over long periods of time. As a result of these advantages, amateurs are frequently first to discover unpredictable events such as storms in the atmospheres of planets and catastrophic explosions of stars. They compete with professionals in discovering transient objects such as comets and asteroids. It often happens that an amateur makes a discovery which a professional follows up with more detailed observation or theoretical analysis, and the results are then published in a professional journal with the amateur and the professional as coauthors.

On Palomar Mountain in California there are two famous telescopes, the huge 200-inch and the little 18-inch. The 200-inch was for many years the largest in the world, exploring the far reaches of the universe with unequaled sensitivity. The 18-inch was on the mountain before the 200-inch and made equally important discoveries. It was the brainchild of the German amateur astronomer Bernhardt Schmidt. Schmidt was a professional optician who made a living by grinding lenses and mirrors. He worked as an unpaid guest at the university observatory in Hamburg. In 1929 he invented a new design for a telescope that produced sharply focused photographic images over a wide field of view. He built and installed the first Schmidt telescope at Hamburg. The Schmidt telescope made it possible for the first time to photograph large areas of sky rapidly. Compared with previously existing telescopes, the Schmidt could photograph about a hundred times more area every night.

The 18-inch at Palomar was the second Schmidt telescope to be built and the first to be used in a mountaintop observatory with good astronomical seeing. Fritz Zwicky, a Swiss professional astronomer, understood the potential of Schmidt’s invention and installed the 18-inch on the mountain in 1935. He used it to do the first rapid photographic sky survey, photographing large areas of sky every night and mapping the positions of hundreds of thousands of galaxies. As a result of this survey, Zwicky made two fundamental discoveries. He found that galaxies have a universal tendency to congregate into clusters. And he found that the visible mass of the galaxies is insufficient to account for the clustering. From the observed positions and velocities of the galaxies, Zwicky calculated that the clusters must contain invisible mass that is about ten times larger than the visible mass. His discovery of the invisible mass, made with the little Schmidt telescope, opened a new chapter in the history of cosmology. Our later explorations of the cosmos have confirmed that Zwicky was right, that the dark unseen mass dominates the dynamics of the universe. Professional and amateur astronomers are using Schmidt telescopes all over the world to continue the revolution that Schmidt and Zwicky started. Schmidt himself did not live to see the triumph of his invention. When Hitler came to power in Germany in 1933, Schmidt was so disgusted that he gave up hope and quietly drank himself to death.

David Levy is an amateur astronomer in the modern style. He observes at his home in Arizona where he has three modest but well-equipped telescopes, two of them of Schmidt design. He has also visited frequently as a guest observer at the Palomar observatory in California, where he collaborates with the professionals. At Palomar he was using Zwicky’s original 18-inch telescope, which was still going strong and making important discoveries after sixty years of intensive use. His collaborators were Eugene and Carolyn Shoemaker, until Eugene’s untimely death in a car accident. Now he continues the collaboration with Carolyn alone.

The most famous event of the collaboration occurred in 1993 when Eugene was still alive. This was the discovery of the comet Shoemaker-Levy 9, which was seen in the process of tidal disruption after passing too close to the planet Jupiter. The newly discovered comet was at that moment breaking up into eighteen pieces. The pieces moved apart until they looked like a string of pearls, stretched out into a straight line, each with its own tail of gas and dust shining in the light of the distant sun. After a few days of careful observation and calculation, it became clear that the pieces of the comet were all destined to crash into Jupiter sixteen months later. This was the first time in the history of astronomy that two celestial objects were seen to collide.


At the time when Jupiter was under bombardment in July 1994, I was lucky to be a guest of the amateur astronomer Gilbert Clark in the dome occupied by a 24-inch telescope on Mount Wilson in California. Clark is a retired Navy officer who founded and directs a charitable foundation called Telescopes in Education, or TIE for short. The 24-inch telescope is on loan from the Mount Wilson Observatory to TIE and is instrumented so that it can be operated by remote control. While Clark and I were in the dome, the telescope was being operated by children in a classroom in Virginia. We could see the same images that the children were seeing, and we could hear their voices. They were deciding where to point the telescope. They looked intermittently at various deep-sky objects, galaxies, and star clusters, but always came back to Jupiter. There on the screen was Jupiter, not the familiar image of Jupiter with bland horizontal bands in its cloudy atmosphere, but a wounded Jupiter with five big black scars at the places where fragments of the comet had struck. To me the most remarkable feature of the view was that we could see Jupiter spinning. The scars made the rotation of the planet visible. Jupiter spins fast, making one revolution in nine hours, forty degrees of longitude per hour. We could see the scars moving across the face of the planet, disappearing at one edge and appearing at the other. And the children could see them too.

Ferris is saying that amateur astronomy is a growth industry, gaining in scientific importance as new technologies increase the reach of amateur instruments. Another factor favoring the amateur observer is the change in our view of the universe caused by recent discoveries. The traditional Aristotelian view imagined the astronomical universe to be a sphere of unchanging peace and harmony. The earth alone was perishable and violent, while the heavenly bodies were perfect and quiescent. This view was contradicted by a multitude of discoveries during the last four hundred years, beginning with the two exploding stars observed by Tycho Brahe and Johannes Kepler and with the mountains and valleys discovered by Galileo on the moon. In the last fifty years it became clear that we live in a violent universe, full of explosions, collapses, and collisions. The Earth now appears to be a comparatively quiet corner in a universe of cosmic mayhem. The 1994 bombardment of Jupiter demonstrated that our own solar system is not immune to cosmic violence. After this replacement of the old static view of the universe by a new dynamic view, the subject matter of astronomy is also transformed. Astronomy is less concerned with things that do not change and more concerned with things that change rapidly. The new emphasis on rapidly changing phenomena requires quick and frequent observation. Quick and frequent observation is a game that serious amateurs can play well. It is a game that amateurs can sometimes play better than professionals. It is a game that gives amateurs and professionals many opportunities for fruitful cooperation.

Ferris shows us a grand vision of the growing importance of ama-teurs, nimble, well-equipped, and well- coordinated, jumping ahead of the slow-moving professionals to open new frontiers. Some professional astronomers share this vision and welcome the help that amateurs can provide. But most professionals consider the efforts of the amateurs trivial. After all, the professionals with their big instruments and big projects are solving the central problems of cosmology, while the amateurs are finding pretty little comets and asteroids. The view of the majority of professionals was expressed by the physicist Ernest Rutherford, the discoverer of the atomic nucleus, who said: “Physics is the only real science, the rest is butterfly-collecting.” For most professional astronomers, the large-scale structure of the universe is real science, while comets and asteroids are unimportant details of interest only to butterfly collectors. Butterfly-collecting is an amiable hobby, but it should not be confused with serious science.

The clash between the two visions of amateur astronomy, Ferris’s vision of amateurs as pioneer explorers and Rutherford’s vision of amateurs as butterfly collectors, has deep roots. It arises from an ancient clash between two visions of the nature of science. There are two kinds of science, known to historians as Baconian and Cartesian. Baconian science is interested in details, Cartesian science is interested in ideas. Bacon said,

All depends on keeping the eye steadily fixed on the facts of nature, and so receiving their images as they are. For God forbid that we should give out a dream of our own imagination for a pattern of the world.

Descartes said,

I showed what the laws of nature were, and without basing my arguments on any principle other than the infinite perfections of God I tried to demonstrate all those laws about which we could have any doubt, and to show that they are such that, even if God created many worlds, there could not be any in which they failed to be observed.

Modern science leapt ahead in the seventeenth century as a result of fruitful competition between Baconian and Cartesian viewpoints. The relation between Baconian science and Cartesian science is complementary. We need Baconian scientists to explore the universe and find out what is there to be explained. We need Cartesian scientists to explain and unify what we have found. Generally speaking, professional astronomers tend to be Cartesian, amateur astronomers to be Baconian. It is right and healthy that there should be a clash between their viewpoints, but it is wrong for either side to treat the other with contempt. Ferris’s sympathies are on the side of the amateurs, but he portrays the professionals with respect and understanding.


Astronomy is the oldest science and has the longest history. For two thousand years it was studied in different ways in two disconnected worlds, the Western world of Babylonia and Greece and Arabia, and the Eastern world of China and Korea. Ancient astronomy in the West was predominantly Cartesian, culminating in the elaborate theoretical universe of Ptolemy, with the clockwork machinery of cycles and epicycles determining how the heavenly bodies should move. Astronomy in the East was Baconian, collecting and recording observations without any unifying theory. In both worlds, astronomy was mixed up with astrology and was mainly studied by professional astrologers. After a promising start, progress stopped and science stagnated for a thousand years, because neither Baconian science nor Cartesian science could flourish in isolation from each other. In the West, theory was unconstrained by new observations, and in the East, observations were unguided by theory.

Then came the great awakening in the West, when Bacon and Descartes together led the way to the flowering of modern science. The seventeenth and eighteenth centuries were the hey-day of the scientific amateurs. During those two centuries, professional scientists like Isaac Newton were the exception and gentleman amateurs like his rival Gottfried Leibniz were the rule. Amateurs had the freedom to jump from one area of science to another and start new enterprises without waiting for official approval. But in the nineteenth century, after two hundred years of amateur leadership, science became increasingly professional. Among the leading scientists of the nineteenth century, professionals such as Michael Faraday and James Clerk Maxwell were the rule and amateurs Charles Darwin and Gregor Mendel were the exceptions. In the twentieth century the ascendancy of the professionals became even more complete. No twentieth-century amateur could stand like Darwin in the front rank with Hubble and Einstein.

If Ferris is right, astronomy is now moving into a new era of youthful exuberance in which amateurs will again have an important share of the action. It appears that each science goes through three phases of development. The first phase is Baconian, with scientists exploring the world to find out what is there. In this phase, amateurs and butterfly collectors are in the ascendant. The second phase is Cartesian, with scientists making precise measurements and building quantitative theories. In this phase, professionals and specialists are in the ascendant. The third phase is a mixture of Baconian and Cartesian, with amateurs and professionals alike empowered by the plethora of new technical tools arising from the second phase. In the third phase, cheap and powerful tools give scientists of all kinds freedom to explore and explain. The most important of the new tools is the personal computer, now universally accessible and giving amateurs the ability to do quantitative science. After the computer, the next-most-important tool is the World Wide Web, giving amateurs access to scientific papers and discussions before they are published, allowing amateurs all over the world to communicate and work together.

Astronomy, the oldest science, was the first to pass through the first and second phases and emerge into the third. Which science will be next? Which other science is now ripe for a revolution giving opportunities for the next generation of amateurs to make important discoveries? Physics and chemistry are still in the second phase. It is difficult to imagine an amateur physicist or chemist at the present time making a major contribution to science. Before physics or chemistry can enter the third phase, these sciences must be transformed by radically new discoveries and new tools. The status of biology is less clear. Mainstream biology is undoubtedly in the second phase, dominated by armies of professionals exploring genomes and analyzing metabolic pathways. But there is a wide hinterland of biology away from the mainstream, where amateurs following the tradition of Darwin discover new species of wildflowers, breed new varieties of dogs and pigeons and orchids, and collect butterflies. The writer Vladimir Nabokov is the most famous of twentieth-century butterfly collectors, but there are many others not so famous who also discovered new species. A young friend of mine who went recently as a student to Ecuador discovered twelve new species of plants in the rain forest.

Biology will probably be the next science to enter the third stage. New tools which might give power to amateur biologists are already visible on the horizon. The new tools will be cheaper and smaller versions of the tools now used by professional biologists to do genetic engineering. It took thirty years for the expensive and cumbersome mainframe computers of the 1950s to evolve into the cheap and convenient personal computers of the 1980s. In a similar fashion, the expensive genome-sequencing and protein-synthesizing machines of today will evolve into cheap machines that can stand on a desktop. The personal computer is not only cheaper and smaller, but also faster and more powerful than the mainframe that it replaced. The desktop sequencers and synthesizers of the future will be faster and more powerful than the machines that they will replace, and will be controlled by more sophisticated computer programs.

When these tools are available, the demand for them will be irresistible, just as the demand for laptop computers is irresistible today. Genetic engineering of roses and orchids, ornamental shrubs and vegetables, will be a new art form as well as a new science. Homeowners in well-to-do suburbs will use the new tools to embellish their gardens, while subsistence farmers in poor countries will use them to feed their families with higher-yielding or better-tasting potatoes. Amateur plant breeders and animal breeders and ecologists and nature lovers will then be enabled to make serious contributions to science, just as amateur astronomers do today.

Before the amateur use of genetic engineering becomes widespread, numerous political and legal obstacles will have to be overcome. Many people are strongly opposed to genetic engineering of any kind. Some of the opposition arises from religious or ideological principles, but much of it arises from practical concerns. Genetic engineering can undoubtedly be dangerous to public health and to ecological stability. The use of genetic engineering kits must be strictly regulated if these dangers are to be avoided. Genetic engineering of microbes is a great tool for terrorists, as Richard Preston demonstrates in his recent book The Demon in the Freezer.* Any kit available to the public must be made physically incapable of handling microbes. It could well happen that political authorities will decide to prohibit such kits altogether. It will be a sad day for biology if amateurs are forbidden the use of tools available to professionals. But that is a decision which we should leave to our grandchildren.

When we look at the wider society outside the domain of science, we see amateurs playing essential roles in almost every field of human activity. Amateur musicians create the culture in which professional musicians can flourish. Amateur athletes, amateur actors, and amateur environmentalists improve the quality of life for themselves and others. Amateur writers such as Jane Austen and Samuel Pepys do as much as the professionals Charles Dickens and Fyodor Dostoevsky to plumb the heights and depths of human experience. In the most important of all human responsibilities, the raising of children and grandchildren, amateurs do the lion’s share of the work. In almost all the varied walks of life, amateurs have more freedom to experiment and innovate. The fraction of the population who are amateurs is a good measure of the freedom of a society. Ferris shows us how amateurs are giving a new flavor to modern astronomy. We may hope that amateurs in the coming century, using the new tools that modern technology is placing in their hands, will invade and rejuvenate all of science.

This Issue

December 5, 2002