An astronomer observes and studies the sun, the planets, the galaxies, the formation of the stars, in a word; the universe! He is a research scientist who supervises and carries out work related to his specialty.
Like any scientist worthy of the name, he starts from his observations to try to transcribe them in theory (he is then an astronomer-theoretician). An astronomer can also be a lecturer and teacher. His ability to popularize his knowledge is often appreciated by the general public.
An astronomer is a night owl (but the profession is changing). Indeed, its activity is partly nocturnal. It is in the darkness that he observes the universe.
It carries out this activity in sites chosen for the quality of the sky, far from pollution produced by men. Using telescopes but also with satellite data or probes, he collects information and analyzes it in the laboratory, on a computer. He tries to describe the physical processes that govern the universe. His work can be published in specialized journals.
An astronomer holds lectures and participates in academic symposia. Note that this professional can design or improve the tools with which he works (telescopes, spectrographs…). It should be known that the position is very limited. Competition is raging among suitors and many are going overseas. The missions of an astronomer, by definition, often have an international character. They, therefore, imply a strong collaboration, many contacts, and exchanges with other countries.
This job requires qualities specific to scientists and researchers: A sense of observation, passion, and creativity. You also need to be able to work in a team. Being bilingual is an advantage.
Good physical conditions are required because the working conditions are very variable. Indeed, an astronomer can work day and night depending on the purpose of his studies: Daytime activity for the observation of the sun, night for the observation of other stars.
In addition, their observatories are located in isolated places where the climate is difficult; extreme heat or cold. We are led to live far from our loved ones. But it should be noted that the profession evolves: Astronomers work more and more with data transmitted by probes or other satellites. This change allows them to exercise with office hours. Like any scientist, Astronomers must be organized and have a synthetic mind.
The practice of astronomy
Why do we become astronomers? The reasons can be very diverse. Many come to this trade after being bitten, very young, by astronomical observation, using a pair of binoculars or a small telescope. The most resourceful among these young people may have even built their own telescope, after patiently polishing the mirrors.
Rarely did the transition from the “before” to the “after” take place.
Others will have been marked by reading a book or a chronicle in a magazine, by watching a program or by a particularly inspiring fortuitous encounter. Still, others grew up in the particularly effervescent period of the Moon race, between 1961 and 1972. Rarely did the transition from the “before” to the “after” take place, it was as striking as during this period. As Carl Sagan has already pointed out, these years occupy a privileged period in the history of humanity, when Moon and planets have ceased to be distant and inaccessible objects and have become worlds in the process of exploration. Can we imagine stronger motivation than the idea of participating in this huge adventure?
Astronomer, then. But is there a typical astronomer? If so, what does it look like? Can they all be Professor Calys, from Hergé’s The Mysterious Star? The answer, thank God, must be nuanced, since there are several kinds of astronomers. The practice of astronomy differs from that of the majority of other scientific disciplines in the important role played by amateurs. This word has, in this context, no pejorative connotation.
As will be seen below, the term “amateur astronomer” is the conventional term used to describe an observer of the sky who uses, as a hobby, a small personal telescope to make astronomical observations. In many cases, these observations may be of great interest to the professional astronomer.
This specificity makes the practice of astronomy one of the most open and democratic scientific activities
Amateur astronomers are a group of practitioners, often as motivated as professional astronomers. They make a remarkable contribution to the development of the discipline through unique observations, occupying a small but neglected niche by professional astronomers. This specificity makes the practice of astronomy one of the most open and democratic scientific activities. In the following overview, it is important to discuss separately the role of professionals and amateurs.
The professional astronomer
The choice of an astronomical career implies not only that passion is at the rendezvous, but also that it is accompanied by other qualities. The work certainly requires minimum skills for the natural sciences and mathematics: Analytical mind, logical reasoning ability, ability to observe and draw from these observations the appropriate conclusions, sensitivity to the beauty and organization of Nature, persistence and determination in the execution of the work.
Also required, this capacity to dose with intelligence, audacity, and prudence, capacity to which the physicist Jean Perrin alluded while speaking about the two “instincts […] whose balance is necessary to the slow progress of the human science”. Beyond these requirements that characterize the exercise of any scientific work, an astronomer is distinguished by his desire to go beyond a mere passive admiration of the starry sky. He asks questions; why is the universe as it is? How is it structured? What will it become?
To tackle such fundamental questions, the astronomer usually focuses on a particular area of research. The divisions between the different fields of research of discipline are always a little arbitrary. The ones I propose reflect a modern reality and are established as follows. Planetary astronomy is concerned with the solar system and its properties.
This domain includes the planets and minor components of this system (planetary satellites, comets, asteroids, meteorites, and interplanetary dust) but generally excludes the Sun. Planetary astronomy frequently crosses the domains of terrestrial geology and climatology, since the processes that constantly change the physiognomy and the climate of our planet can also be at work on other objects of the solar system.
Today, this discipline mainly uses observations made by probes (such as the Cassini / Huygens mission towards Saturn and Titan, or the Mars Exploration Rover mission which deposited Spirit and Opportunity on the Martian surface) rather than observations. traditional telescopic.
In recent years, planetary astronomy has also included the search for “exoplanets”, which has become possible thanks to the development of very sensitive observation techniques. Stellar astronomy, on the other hand, is concerned with the study of the physical properties and evolution of stars in general. The study of the Sun must in principle be integrated into this branch, although the links between solar and stellar communities are not as close as one might imagine.
Galactic astronomy focuses on the properties of the galaxy; this stellar system comprises about a hundred billion stars as well as gas and dust, distributed irregularly between the stars. Our modern vision of the Milky Way also requires the presence in this system of a huge amount of “dark matter”. This is exotic matter, in a form different from the one we are familiar with, which has never been observed directly, but whose presence is felt in the galaxy through the gravitational force it exercises.
Extragalactic astronomy focuses on the study of the physical properties and spatial distribution of external galaxies. These stellar systems analogous to the Milky Way, which are the basic building blocks of the largest structures in the universe. Finally, modern cosmology is concerned with the universe at its greatest scale, its structure, its geometry and its dynamics, and it makes a large part of the study of its evolution. What did the initial phases of the development of the universe, those that follow the primordial explosion, and how will the universe evolve?
In these areas, the astronomer tackles the problems that fascinate him. They are legion, but ambition and pragmatism control these choices. A scientist strives, during his career, to work on the most interesting problems possible while recognizing that he can be particularly willing – because of his abilities, his training or his interests – to face one kind of problem rather than another. The progress made is often incremental, but any scientist certainly has the ambition to be interested in problems whose solution will advance his field in the most significant way possible.
The idea of advancing a field of science, even incrementally, is exciting. This result, however, is not obtained overnight; it requires a long preparatory work. Just like the athlete who has to invest long hours in his training before reaching an international level, the scientific apprentice has to “go to school”. He is therefore required to understand and master the language and basic concepts of mathematics, physics, and astronomy. His training must be as wide as possible, in order to be able to show some distance in his discipline.
Then, the beginner must digest the results obtained by those who preceded before being able to aspire to advance the field he has chosen. All this takes time and requires patience, determination, tenacity – in a word, work. Although history shows that such work can be done outside the academic context, such cases are rare today. The outstanding theoretical work done by Einstein in his golden year (1905) while working out of the academic circuit at the Berne Patent Office is the exception that proves the rule.
The way a young scientist today “goes to school” differs considerably from the way a student of literature does, for example. More specifically, the body of a discipline such as astronomy or physics includes few primary sources. For example, no astronomer – apart from those who are particularly interested in the history of science – has read Johannes Kepler’s Astronomia nova (1609) and Harmonices mundi (1619), in which are set forth for the first time, respectively, the first and second laws, and the third law of planetary motion (also known as Kepler’s laws).
In the same way, few contemporary physicists have passed through the Philosophië naturalis principia mathematica (1687), yet the key text of Newtonian mechanics. This does not, however, prevent the teachers we are from making a large part of this subject in our courses, since the content of these primary sources has been – since the seventeenth century – proven, digested and reformulated in a modern language and accessible to all.
There is, therefore, no greater interest in returning to original texts in Latin, which are also often characterized by anachronistic terminology and mathematical tools with which contemporary scientists are generally uncomfortable. This situation differs from that of the student of literature preparing a thesis on the naturalistic doctrine which would have, him, the obligation to read the novels of Zola rather than condensed modern.
In this patient construction company, science can occasionally go astray.
So, project by project, the discipline develops. The image of a building, patiently constructed, brick by brick, is appropriate. Each brick, taken individually, is a contribution that may seem modest; the final building will be no less majestic. In this patient construction company, science can occasionally go astray. Thus, several famous astronomers of the late nineteenth century observe channels on the surface of Mars, and the idea that they are artificial – built by an intelligent species – is accepted in the enthusiasm by the great astronomers that were Camille Flammarion and Percival Lowell.
This incident elegantly illustrates the sometimes slow capacity for self-correction associated with the scientific process. It was only after the Mariner 9 mission, in 1971, that astronomy made its final mourning of the myth of the Martian canals.
The amateur astronomer
In parallel with the scientific activity of the professional astronomer exists, as I said, an activity pursued by amateur astronomers. Who are they and what are they doing? Most of them are astronomy buffs who usually do not have specialized training in this field. By day, they practice all kinds of professions that often have nothing to do with astronomy.
When the sun goes down, they take out their telescopes and get to work. A small number of them have built these small masterpieces with their hands, patiently polishing their optical components. Others invest in quality commercial systems. All, however, share a contagious enthusiasm for observing the sky, which they undoubtedly know better than a large fraction of professional astronomers. Some amateurs spend the majority of their time observing objects accessible to small telescopes: double or variable stars, clusters of various stars, nebulae, and outer galaxies populate this universe.
Others push the exercise to try to observe the hundred items cataloged by the great astronomer of the eighteenth century, Charles Messier. Some go beyond astronomy as a hobby and do some original observation work. The most famous amateur astronomers hunt comets, as Messier did 250 years ago. Many of these items are named after amateur astronomers who discovered them, such as William Bradfield, Don Machholz and Leslie Peltier.
A minority, superbly equipped, is dedicated to the search for supernovae in external galaxies using telescopes completely automated and controlled remotely! The type of observations that amateur astronomers contribute most effectively is – for practical reasons – not actively pursued by professionals. The search for comets and supernovae, for example, requires the repeated observation of large areas of the sky, a task that can be performed effectively by a serious amateur equipped with a telescope of modest size.
The niche occupied by amateur astronomers has been somewhat neglected by professional astronomers.
The professional usually has to deal with a limited number of nights of observation on a larger telescope, a combination more appropriate for other kinds of projects, such as the detailed study of a limited number of objects. For these reasons, the niche occupied by amateur astronomers has been somewhat neglected by professional astronomers, which contributes to a synergy between the two groups particularly interesting and probably unique in science.
In the majority of cases, the work of the amateur astronomer ends with the discovery of a new object, its announcement and its confirmation by the networks of professional observatories. Subsequent work, which includes the acquisition of various types of data, their modeling, and interpretation, is generally the responsibility of the professional, as this work requires means far beyond those available to an amateur astronomer.
Contrary to what one might think, “official science” does not deprive itself of recognizing the talent and the contribution to the discipline of those who, without prior professional training, contribute in such an essential way. Thus, David Levy, whose name is associated with the comet Shoemaker-Levy 9 which crashed on Jupiter in 1994, holds several doctorates honoris causa. The case of Milton Humason is perhaps, in this context, the most edifying.
Humason is first employed to drive the mules that carry the materials required for the construction of the observatory atop Mount Wilson, California. In 1917 he was hired as a janitor at the Observatory, where he was quickly promoted to night assistant. Because of his observational skills, he is entrusted with the Nebula Redshift Measurement Program, in which he becomes the valuable collaborator of the great astronomer Edwin Hubble. Ultimate consecration of the little muleteer, Humason ended his career with the title of astronomer at the observatories of Mount Wilson and Palomar and an honorary doctorate from the University of Lund, Sweden.