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
- SECTION I COMETS WHOSE RETURN HAS NOT BEEN VERIFIED BY OBSERVATION
- SECTION II INTERIOR COMETS, OR COMETS OF SHORT PERIOD, THAT HAVE NOT YET RETURNED
- SECTION III COMETS OF MEAN PERIOD
- SECTION IV COMETS OF LONG PERIOD
- 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 III - COMETS OF MEAN PERIOD
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
- SECTION I COMETS WHOSE RETURN HAS NOT BEEN VERIFIED BY OBSERVATION
- SECTION II INTERIOR COMETS, OR COMETS OF SHORT PERIOD, THAT HAVE NOT YET RETURNED
- SECTION III COMETS OF MEAN PERIOD
- SECTION IV COMETS OF LONG PERIOD
- 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
Periodical comets exterior to the solar system; the type of this class is Halley's comet, which is tile only comet of mean period whose return has been verified by observation–Enumeration of comets with periods between 69 and 200 years– Periods; aphelion and perihelion distances.
Of the comets belonging to this class Halley's comet is the type; but it is the only one of which we have several undisputed apparitions. When a comet is suspected to be identical with some other comet that has been previously observed, from the similarity of the parabolic elements, its return is probable; but as a rule great uncertainty attaches to the length of the period, even if, assuming the identity of the two comets, the perturbations be left out of the question. A third apparition is, therefore, generally necessary before the identity and real periodicity of a comet can be affirmed. And this third element up to the present time is wanting in the comets we are now engaged upon. But it will evidently suffice to prove a second apparition, when the elliptic elements have been calculated solely from observations of the first apparition.
The following, in the order of their discovery, are the nine comets of mean period which we have to mention:–
The first on the list is the comet of 1532, observed by Apian and by Fracastoro, ‘ whose head,’ says the latter observer, ‘ was three times larger than Jupiter, with a beard two fathoms long.’
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- Information
- The World of Comets , pp. 141 - 143Publisher: Cambridge University PressPrint publication year: 2010