Book contents
- Frontmatter
- EDITOR'S PREFACE
- PREFACE
- Contents
- LIST OF ILLUSTRATIONS
- CHAPTER I BELIEFS AND SUPERSTITIONS RELATIVE TO COMETS
- CHAPTER II COMETARY ASTRONOMY UP TO THE TIME OF NEWTON
- CHAPTER III THE MOTIONS AND ORBITS OF COMETS
- CHAPTER IV PERIODICAL COMETS
- CHAPTER V PERIODICAL COMETS
- CHAPTER VI THE WORLD OF COMETS AND COMETARY SYSTEMS
- CHAPTER VII PHYSICAL AND CHEMICAL CONSTITUTION OF COMETS
- CHAPTER VIII PHYSICAL TRANSFORMATIONS OF COMETS
- CHAPTER IX MASS AND DENSITY OF COMETS
- CHAPTER X THE LIGHT OF COMETS
- CHAPTER XI THEORY OF COMETARY PHENOMENA
- CHAPTER XII COMETS AND SHOOTING STARS
- SECTION I WHAT IS A COMET?
- SECTION II IS THE MATTER OF COMETS DISPERSED IN THE INTERPLANETARY SPACES
- SECTION III COMETS AND SWARMS OF SHOOTING STARS
- SECTION IV COMMON ORIGIN OF SHOOTING STARS AND COMETS
- CHAPTER XIII COMETS AND THE EARTH
- CHAPTER XIV PHYSICAL INFLUENCES OF COMETS
- CHAPTER XV SOME QUESTIONS ABOUT COMETS
- I ELLIPTIC ELEMENTS OF THE RECOGNISED PERIODICAL COMETS OF THE SOLAR SYSTEM
- II GENERAL CATALOGUE OF THE ORBITS OF COMETS
- Plate section
SECTION I - WHAT IS A COMET?
Published online by Cambridge University Press: 05 March 2012
- Frontmatter
- EDITOR'S PREFACE
- PREFACE
- Contents
- LIST OF ILLUSTRATIONS
- CHAPTER I BELIEFS AND SUPERSTITIONS RELATIVE TO COMETS
- CHAPTER II COMETARY ASTRONOMY UP TO THE TIME OF NEWTON
- CHAPTER III THE MOTIONS AND ORBITS OF COMETS
- CHAPTER IV PERIODICAL COMETS
- CHAPTER V PERIODICAL COMETS
- CHAPTER VI THE WORLD OF COMETS AND COMETARY SYSTEMS
- CHAPTER VII PHYSICAL AND CHEMICAL CONSTITUTION OF COMETS
- CHAPTER VIII PHYSICAL TRANSFORMATIONS OF COMETS
- CHAPTER IX MASS AND DENSITY OF COMETS
- CHAPTER X THE LIGHT OF COMETS
- CHAPTER XI THEORY OF COMETARY PHENOMENA
- CHAPTER XII COMETS AND SHOOTING STARS
- SECTION I WHAT IS A COMET?
- SECTION II IS THE MATTER OF COMETS DISPERSED IN THE INTERPLANETARY SPACES
- SECTION III COMETS AND SWARMS OF SHOOTING STARS
- SECTION IV COMMON ORIGIN OF SHOOTING STARS AND COMETS
- CHAPTER XIII COMETS AND THE EARTH
- CHAPTER XIV PHYSICAL INFLUENCES OF COMETS
- CHAPTER XV SOME QUESTIONS ABOUT COMETS
- I ELLIPTIC ELEMENTS OF THE RECOGNISED PERIODICAL COMETS OF THE SOLAR SYSTEM
- II GENERAL CATALOGUE OF THE ORBITS OF COMETS
- Plate section
Summary
The ancients were unacquainted with the physical nature of comets–False ideas entertained by astronomers of the eighteenth century respecting the physical constitution of comets; comets regarded by them as globes, nearly similar to the planetary spheroids–Views of Laplace upon comets, compared by him to nebulae–Contemporary astronomers have confirmed these views and rectified the errors of the ancient hypotheses–Desideratum of science ; the rencontre of the earth with a comet or the fragment of a comet.
The question, What is a comet? examined in the preceding chapter, and which we reproduce as the heading of this Section, has been the subject of numerous hypotheses. It cannot, however, yet be considered as answered. But it has lately been attempted in an entirely new manner, and by a method least of all to be expected–that of direct investigation. The exposition of this method, and the considerations which have led to it, will be the object of this new chapter.
Let us commence by recapitulating the substance of what our previous enquiries and researches have already taught us.
The ancients, as we have seen at the commencement and in the course of this work, held notions concerning the nature of comets that were entirely hypothetical, and moreover contradictory. On passing their conjectures in review it is surprising, no doubt, to meet with ideas, to some extent, in conformity with the accepted facts of modern science.
- Type
- Chapter
- Information
- The World of Comets , pp. 417 - 421Publisher: Cambridge University PressPrint publication year: 2010First published in: 1877