CHAPTER II.

PHENOMENA OF THE HEAVENS, AS SEEN FROM DIFFERENT PARTS OF THE SOLAR SYSTEM.

SECTION I.-PROSPECT AT THE SUN.

To a spectator at the centre of the system, the planets would appear to move in harmonious order from west to east. He would probably have no means of determining their several distances, but might suppose those farthest distant, which are longest in performing a revolution. Unaoquainted with our method of computing time, he would probably take the period of Mercury, with which to compare the periods of the other planets. He would form a conjecture of the magnitude of different bodies, from their apparent diameters compared with the time of their revolutions.

All would not appear to move in the same orbits; but, their paths would seem to cross each other at very small angles. If he should make the path of one of the planets a standard, the paths of all the rest would be inclined to it, one half being on one side, and the other half on the other side of the standard. As in equal times they describe equal areas, the spaces passed in a given time, in different parts. of the orbits would be unequal, because the orbits are elliptical. The apparent diameters would also vary a little at different times. All the stars would appear at rest, and equally distant.

SECTION 11.-PROSPECT AT MERCURY.

To a spectator at Mercury a different view would be presented. Being by the whole of Mercury's orbit nearer to the other planets, at some times than at others, their apparent diameters would to him vary in proportion to their dis