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
- SECTION I COMETS PARTICIPATE IN THE DIURNAL MOTION
- SECTION II MOTIONS OF COMETS
- SECTION III IRREGULARITIES IN THE MOTIONS OF COMETS
- SECTION IV THE ORBITS OF COMETS
- SECTION V THE ORBITS OF COMETS COMPARED WITH THE ORBITS OF THE PLANETS
- SECTION VI DETERMINATION OF THE PARABOLIC ORBIT OF A COMET
- 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
- 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 - COMETS PARTICIPATE IN THE DIURNAL MOTION
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
- SECTION I COMETS PARTICIPATE IN THE DIURNAL MOTION
- SECTION II MOTIONS OF COMETS
- SECTION III IRREGULARITIES IN THE MOTIONS OF COMETS
- SECTION IV THE ORBITS OF COMETS
- SECTION V THE ORBITS OF COMETS COMPARED WITH THE ORBITS OF THE PLANETS
- SECTION VI DETERMINATION OF THE PARABOLIC ORBIT OF A COMET
- 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
- 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
Comets participate in the diurnal motion of the heavens. During the time of their apparition they rise and set like the sun, the moon, the stars, and the planets. In this respect, therefore, they do not differ from other celestial bodies.
Let the observer, when a comet is in sight, note the point in the heavens which it occupies when his attention is first directed to it. This is easily done by referring the nucleus, the brilliant point from which the tail proceeds, to two adjacent stars. Let a certain time elapse–an hour, for example; at the end of that time the three luminous points, the two stars and the comet, will be found to have changed their position with respect to the horizon, each having described an arc of a circle in the heavens. The common centre of these arcs is the celestial pole, a point situated within a very small distance of the pole-star; the lengths of these arcs depend upon the interval of time between the observations, and the angular distance of each body from the pole. The direction is that of the general movement of the heavens and the stars; that is to say, from east to west.
We have here, then, a fact which clearly teaches us that a comet moves in regions beyond the atmosphere of the earth; for the diurnal motion is an apparent motion, foreign to the comet, and belongs in reality to the observer, or, as we may say,to the observatory.
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- Information
- The World of Comets , pp. 59 - 60Publisher: Cambridge University PressPrint publication year: 2010First published in: 1877