AND SOLAR SYSTEMS DIFFERENT FROM OURS.
EACH of the stars which glitter in the depths of space is a voluminous and massive sun like that which gives light to our earth. Distance alone reduces them to the appearance of fixed points. If we could approach any one of them we should experience the same impression as in passing from Neptune to the sun; the star would increase in size as we should approach it; it would soon exhibit a circular disk and continue to increase its proportions until they would be as large as the sun; finally, this luminous disk, continuing to increase in consequence of our approach, would expand and present itself as a fiery furnace filling the entire heavens—a colossal blaze, under which we would be reduced to nothing, melted like wax, vaporized like a drop of water dropped on red-hot iron! Such is every star in the heavens.
Each sun in space has its special sphere of attraction, a sphere which extends to the limit of neutralization by another. This attraction diminishes in the inverse ratio of the square of the distances, but never becomes absolutely nothing. At the distance of Neptune the solar attraction is 900 times less than at the distance of the earth. While the earth if it were stopped in its course would fall toward the sun 294 hundred-thousandths of a metre during the first second of time, Neptune would fall only 327 hundred-millionths of a metre in the same time. At the aphelion distance of the comet of 1680 the fall toward the sun is only the minute distance of 416 hundred-billionths of a metre during the first second of time. This attraction continues thus to decrease as the distance increases. But, at the same time, if a body moves in the direction of one of the neighboring stars, it begins immediately to receive its influence. The star nearest us is at a distance 210,000 times greater than that which separates the earth from the sun, or eight trillions of leagues; it is the star Alpha Centauri, a brilliant double star whose orbit and mass I have calculated. This mass is equal to the half of that of the sun; it happens that if one could travel from the sun to this star a point would be reached where the attraction of the two would neutralize each other; this point is three-quarters of the distance which separates us, that is, six trillions of leagues from our sun, or, what is the same, two trillions of leagues from Alpha Centauri, the whole distance being eight trillions. At that point, a celestial body, a comet, would hesitate as to which course to pursue, would weigh nothing, would
- Translated from the French by P. A. Towne.