Description

Immediate dispatch from Somerset. Nice older book in good condition. Pages in good condition. Some tanning and marking due to age. No notes or highlighting. See images. Fantastic book.

About the book >.>.> From our experience of the sequence of day and night it is clear that the relation of the Earth to the Sun undergoes cyclic change. Nowadays we explain this diurnal progression in terms of a rotation of the Earth. If for the moment we think of the Sun as being always in a fixed direction and of the Earth as spinning about an axis as in Figure 1.1 it is easy to see that each complete rotation of the Earth will produce a cycle of day and night. Astronomical history shows that even this simple concept was not easily arrived at. Figure 1.1 implies that we are all being continuously whirled around by the Earth’s motion. Why are we not aware of this motion? This question was a serious puzzle to astronomers in ancient times. It remained a mental obstacle until the time of Copernicus (1473-1543). In modern science we know that it is irregularities of motion of which we are aware not smooth motion itself. A huge expensive car moving at 60 M.P.H. on an excellent highway gives much less awareness of motion than a small car driven at 30 M.P.H. along a rough road. By everyday practical standards the Earth’s motion is exceedingly smooth not only in its rotation but in its revolution around the Sun. A plane through the center of the Earth taken at right angles to the axis of rotation meets the surface of the Earth at an imaginary circle called the