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
- SECTION I COMETS PHYSICALLY CONSIDERED
- SECTION II COMETARY NUCLEI, TAILS, AND COMÆ
- SECTION III COMETS DEVOID OF NUCLEUS AND TAIL
- SECTION IV DIRECTION OF THE TAILS OF COMETS
- SECTION V NUMBER OF TAILS
- SECTION VI DIFFERENT FORMS OF TAILS
- SECTION VII LENGTH OF TAILS
- SECTION VIII FORMATION AND DEVELOPMENT OF TAILS
- SECTION IX BRILLIANCY OF COMETS
- SECTION X DIMENSIONS OF NUCLEI AND TAILS
- 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 IV - DIRECTION OF THE TAILS OF COMETS
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
- SECTION I COMETS PHYSICALLY CONSIDERED
- SECTION II COMETARY NUCLEI, TAILS, AND COMÆ
- SECTION III COMETS DEVOID OF NUCLEUS AND TAIL
- SECTION IV DIRECTION OF THE TAILS OF COMETS
- SECTION V NUMBER OF TAILS
- SECTION VI DIFFERENT FORMS OF TAILS
- SECTION VII LENGTH OF TAILS
- SECTION VIII FORMATION AND DEVELOPMENT OF TAILS
- SECTION IX BRILLIANCY OF COMETS
- SECTION X DIMENSIONS OF NUCLEI AND TAILS
- 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
Direction of the tail opposite to the sun; discovered by Apian; the Chinese astronomers were acquainted with this law–Deviations in some comets–Variable aspect of the tail according to the relative positions of the comet, the earth, and the sun.
In respect to the direction of cometary tails let us call attention to an important point–to a general phenomenon which was remarked by the ancients, in the very earliest times. Seneca refers to it in the following line:–
Comas radios solis effugiunt.
The comæ of comets fly the ray a of the sun. According to Edward Biot the Chinese astronomers had observed, since the year 837. this constant direction of cometary tails from the sun. ‘ In Europe, ’ says Lalande, ‘ Apian was the first to perceive that the tails of comets were always opposite to the sun; this rule was afterwards confirmed by Gemma Frisius, Cornelius Gemma, Fracastoro. and Cardan. Nevertheless, Tycho Brahe did not believe it to be very general or well demonstrated; but the fact itself is beyond a doubt. ’
Pingré observes with truth that the direction of the tail is not always strictly opposite to the sun. He instances the comet of 1577, whose tail was deflected as much as 21° towards the south, and the great comet of 1680, when the deflection was about 4 ½°. On both these occasions, however, the comet and the earth occupied the same relative positions in the heavens.
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- The World of Comets , pp. 206 - 208Publisher: Cambridge University PressPrint publication year: 2010