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
- SECTION I COMETS AND THE ASTRONOMERS OF EGYPT AND CHALDEA
- SECTION II COMETARY ASTRONOMY IN THE TIME OF SENECA
- SECTION III COMETS DURING THE RENAISSANCE AND UP TO THE TIME OF NEWTON AND HALLEY
- SECTION IV NEWTON DISCOVERS THE TRUE NATURE OF COMETARY ORBITS
- 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
- 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 - NEWTON DISCOVERS THE TRUE NATURE OF COMETARY ORBITS
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
- SECTION I COMETS AND THE ASTRONOMERS OF EGYPT AND CHALDEA
- SECTION II COMETARY ASTRONOMY IN THE TIME OF SENECA
- SECTION III COMETS DURING THE RENAISSANCE AND UP TO THE TIME OF NEWTON AND HALLEY
- SECTION IV NEWTON DISCOVERS THE TRUE NATURE OF COMETARY ORBITS
- 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
- 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
Newton's Principia and the theory of universal gravitation–Why Kepler did not apply to comets the laws of the planetary movements–Newton discovers the true system of cometary orbits–Halley and the comet of 1682; prediction of its return.
Kepler, in 1618, had already discovered the three laws upon which his fame rests, and which will render his name immortal. These laws govern the movements of bodies which, like the planets and the earth, revolve about the sun in regular periods. In virtue of the first law the orbit described about the sun is an ellipse, of which the sun itself occupies one of the foci; the second relates to the velocity of the planet, a velocity which is greater the nearer the planet is to the sun, and less in proportion as it is further removed; or more accurately the velocity is such that the areas of the sectors swept out by the radius vector of the planet are equal in equal times; hence it follows that the maximum of speed takes place at the perihelion, and the minimum at the aphelion. The third law expresses the constant relation which connects the duration of each periodic revolution with the longest diameter, or major axis of the orbit.
- Type
- Chapter
- Information
- The World of Comets , pp. 52 - 56Publisher: Cambridge University PressPrint publication year: 2010