Book contents
- Frontmatter
- PREFACE
- Contents
- INTRODUCTION
- Part I PROGRESS OF ASTRONOMY DURING THE FIRST HALF OF THE NINETEENTH CENTURY
- Part II RECENT PROGRESS OF ASTRONOMY
- CHAPTER I FOUNDATION OF ASTRONOMICAL PHYSICS
- CHAPTER II SOLAR OBSERVATIONS AND THEORIES
- CHAPTER III RECENT SOLAR ECLIPSES
- CHAPTER IV SPECTROSCOPIC WORK ON THE SUN
- CHAPTER V TEMPERATURE OF THE SUN
- CHAPTER VI THE SUN'S DISTANCE
- CHAPTER VII PLANETS AND SATELLITES
- CHAPTER VIII PLANETS AND SATELLITES (continued)
- CHAPTER IX THEORIES OF PLANETARY EVOLUTION
- CHAPTER X RECENT COMETS
- CHAPTER XI RECENT COMETS (continued)
- CHAPTER XII STARS AND NEBULÆ
- CHAPTER XIII METHODS OF RESEARCH
- INDEX
CHAPTER VI - THE SUN'S DISTANCE
Published online by Cambridge University Press: 07 September 2011
- Frontmatter
- PREFACE
- Contents
- INTRODUCTION
- Part I PROGRESS OF ASTRONOMY DURING THE FIRST HALF OF THE NINETEENTH CENTURY
- Part II RECENT PROGRESS OF ASTRONOMY
- CHAPTER I FOUNDATION OF ASTRONOMICAL PHYSICS
- CHAPTER II SOLAR OBSERVATIONS AND THEORIES
- CHAPTER III RECENT SOLAR ECLIPSES
- CHAPTER IV SPECTROSCOPIC WORK ON THE SUN
- CHAPTER V TEMPERATURE OF THE SUN
- CHAPTER VI THE SUN'S DISTANCE
- CHAPTER VII PLANETS AND SATELLITES
- CHAPTER VIII PLANETS AND SATELLITES (continued)
- CHAPTER IX THEORIES OF PLANETARY EVOLUTION
- CHAPTER X RECENT COMETS
- CHAPTER XI RECENT COMETS (continued)
- CHAPTER XII STARS AND NEBULÆ
- CHAPTER XIII METHODS OF RESEARCH
- INDEX
Summary
The question of the sun's distance arises naturally from the consideration of his temperature, since the intensity of the radiations emitted as compared with those received and measured, depends upon it. But the knowledge of that distance has a value quite apart from its connection with solar physics. The semi-diameter of the earth's orbit is our standard measure for the universe. It is the great fundamental datum of astronomy–the unit of space, any error in the estimation of which is multiplied and repeated in a thousand different ways, both in the planetary and sidereal systems. Hence its determination has been called by Airy “the noblest problem in astronomy.” It is also one of the most difficult. The quantities dealt with are so minute that their sure grasp tasks all the resources of modern science. An observational inaccuracy which would set the moon nearer to, or farther from us than she really is by one hundred miles, would vitiate an estimate of the sun's distance to the extent of sixteen million! What is needed in order to attain knowledge of the desired exactness is no less than this: to measure an angle about equal to that subtended by a halfpenny 2000 feet from the eye, within a little more than a thousandth part of its value.
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- A Popular History of Astronomy During the Nineteenth Century , pp. 269 - 287Publisher: Cambridge University PressPrint publication year: 2010First published in: 1885