From his childhood he showed a deep interest in the natural sciences, astronomy, physics, chemistry, meteorology, geology and in particular botany. At the age of about sixteen his interest turned exclusively to pure mathematics.

Before moving from Skien, I largely took care of myself and enjoyed science, particularly botany and astronomy. Every evening, when the weather was clear, I had the star map in front of me and learned to recognise different stars and planets from the map. I plotted their positions, sitting for several hours on the platform with paper, pen and a flash-light in hand. My only regret was that my father told me to become an astronomer I had to learn mathematics, which would be very difficult. That frightened me. Later, however, I came to a different understanding about learning mathematics.

Walking the streets of the capital, he observed people's expressions, behaviours, and clothes. He wondered how to preserve these scenes. Cameras at the time were large and static, yet Carl wanted to capture a specific moment, a smile, or a movement - especially of one young lady he admired. His youthful love, however, was no match for his shyness, which he couldn't overcome, especially since he did not know the lady personally. He simply wanted her photograph. Easier said than done, but he had access to the latest inventions and his own genius. ... Carl invested in a spy camera, the CP Stirn.

I was a young 19 year-old student at the time and had got hold of a funny detective camera. It was a round flat canister hidden under my vest with the lens sticking out through a buttonhole. Under my clothes I had a string down through a hole in my trouser pocket, and when I pulled the string the camera took a photo. I strolled down Carl Johan, found myself a victim, greeted them, got a gentle smile and then I pulled the string. I took six images at a time and then I went home to change the plate.

I just finished a new paper which I feel should be published as soon as possible. When I went to Societé Mathématique for the first time, I was well prepared and having written a short summary for oral presentation in French. Meetings always start with the president asking for "une communication à faire" or whether anyone has a work he wishes to present. One never announces a presentation beforehand. I informed him at once that I had a contribution. When called, I went to the board and started my presentation. I was told beforehand that I should not write long and complicated mathematical equations, but try to use simple forms. The audience is not supposed to applaud or clap hands. During this meeting 15 mathematicians were present. They and I were in formal evening dress.

I started my presentation with contempt for death. I felt it was better to jump in than to crawl. However, the printed version is more important. I tried to speak slowly and distinctly, as my French is far from fluent. However, I splashed a lot of chalk dust onto my evening dress, so by the time I finished it was almost white, but I did not notice this before I sat down. I finished with an apology for my French, but the President responded that he experienced no difficulty understanding my talk. On the way back to my seat I passed the secretary and handed him my manuscript. During my presentation I brought a book with notes to help with the presentation, but forgot to take it back with me. The first thing the next speaker did was to hand it to me, with a kindly smile. I promised myself that this would never happen again, because it clearly showed that I was very nervous. Next time, I promise not to be nervous, spill chalk dust or forget my notes.

After the presentations, we had an informal gathering at which I was asked a few questions regarding my work. On the way back to my apartment, I walked most of the way with the secretary of Societé Mathématique.

Over many years [Størmer] made or organised such calculations, finding a great variety of orbits. His papers on this subject constitute a major part of his life's work; they number at least 48. Many are short, and in several cases he published brief accounts of the same work in different languages and journals. But many of the papers are very substantial in length and content.

The ingenious corpuscular theory of polar lights, first experimentally studied by Birkeland in 1896 and later developed mathematically by Størmer and very recently illustrated by the refined experiments on periodic electron paths by Brüche, remains our most important attempt to explain the origin and nature of auroras and many apparently related geophysical phenomena. A large part of the article is properly devoted to these important studies in the development of which the author has had no small part. The latter portion of the article contains a good exposition of the present status of this work.

On the whole this paper may be characterised as a review of the special work to which Størmer has devoted many years of study. Its perusal discloses the many problems common to different fields of terrestrial and cosmical physics, possibly susceptible of elucidation through investigation of polar-light phenomena. That some light indeed may be shed on these in the near future the present activity in auroral study affords much hope.

... found it necessary to obtain more facts about the aurora in order to compare theory and observation. A photographic method designed to determine, among other things, the height and position of aurora was therefore developed and successfully applied. The chief results obtained from the analysis of a vast number of parallactic photographs are discussed in this book.

Several monographs and articles on the Aurora have appeared in recent years: it is especially gratifying that the latest book on one of the most impressive of natural phenomena should be written by the man who more than any other has enriched the subject - Carl Størmer. As he tells us in the Preface, he began his career as a Pure Mathematician but the chance demonstration by his colleague Kristian Birkeland of the beautiful experiments on cathode rays moving in the presence of a magnetic field changed his whole future. Henceforth his whole interest was directed to the study and observation of the aurora and the author has here collected in book form the whole of his researches on the aurora.

The book is divided into two parts: the first gives an account of the observation, position and classification of aurorae. The second part is an account of Størmer's researches on the motion of a charged particle in the field of a magnetic dipole begun in 1903 and continued almost uninterrupted to the present day. The variety of orbits possible (amply illustrated by the many beautiful plates) is testimony of the great mathematical difficulty of the problem and also of the infinite patience of the man who pursued this laborious task. It is gratifying that this part of his theoretical researches has found a permanent place in the theory of cosmic rays. Its bearing on auroral theory is less certain though some features of it may be incorporated in an eventual theory. The typography of the book is excellent as was to be expected of a production from the Clarendon Press.

Many fine photographs by Størmer and his colleagues illustrate this part of the book. To Størmer the photographer we owe the development of the parallactic method of determining auroral heights.

It might be a source of interest to many to observe, in the development of my photographic work, what may result when a pure mathematician happens to be an enthusiastic amateur photographer.

His lectures were of great importance to all us young students. They excelled in French elegance combined with clarity and simplicity. Particularly, Størmer's seminar was of great importance to all who were interested in mathematics. For graduate students, Størmer concentrated on Sophus Lie's transformation groups, gamma functions and elliptic functions. All acknowledged and appreciated his deep insights into these theoretical constructs.

... a rather large and bulky slow-moving man. ... He liked the pleasures of the table, good food and wine; he liked the theatre and the opera, and took with him opera glasses the better to observe the action and the danseuses.

Dear Professor Størmer,

Members of this Colloquium on Auroral Physics have invited me to say to you, on their behalf, how pleased we have all been that you found it possible to come from Norway to be present with us at our Conference. We recognise in you the world authority in this field, in which you have been a pioneer and leader for very many years. We see combined in you gifts rarely found together, those of a pure mathematician and those of a national philosopher, theoretical and observational. You have enriched the literature of auroral physics with your mathematical papers on charged particles moving in a magnetic dipole field, as suggested by Birkeland's classical experiments. You have been the pioneer in auroral stereo-photography, for the determination of the height and geographic location of aurorae, and most of our knowledge of this subject is due to you. You have obtained, with the aid of many colleagues whom you have inspired, an enormous number of pairs of photographic plates of aurorae; you have measured and discussed them individually and statistically, and there remain a great quantity still to be discussed by you and others. One of the fruits of this work is the fascinating discovery of the remarkable sunlit aurorae. You have contributed to the study of the auroral spectrum, and your classification of auroral forms has been the basis of the International Auroral Atlas, which has been of great value to many other auroral observers, and has just been reissued for another period of fruitful life

But auroral studies have not fully absorbed your powers. You have used your auroral organisation also for the study of other interesting natural phenomena, such as the luminous night clouds, the mother-of-pearl clouds, and meteor trails. And your work and interest have extended beyond the bounds of physical science into botany and zoology. I need only refer to your practical skill in the production and discipline of unruly mice! (He made his handkerchief behave like a rat - to the great amusement for the participants.)

You have come from far to attend and add distinction and fruitfulness to our meetings. You have thus also given, to those of us who have long known you, the pleasure of renewed companionship, and to those who have hitherto known you only through your writings, the satisfaction of meeting you personally. You have made valued contributions to our lectures and discussions, and we hope that you will carry back with you some additions to your great store of auroral knowledge, which may enhance the value of the book of aurorae you are now writing, to whose appearance we are all looking forward.

We have unitedly felt that we should like you to take back with you some small memento of your time with us. I have much pleasure in asking you, in the name of us all to accept this little gift of a lighter, as a mark of our affectionate esteem, with our good wishes to you for a safe journey home, and a long continuance of your work in auroral physics.