The uses of astronomy

by Edward Everett

Numerous as are the heavenly bodies visible to the naked eye, and glorious as are their manifestations, it is probable that in our own system there are great numbers as yet undiscovered. Just two hundred years ago this year, Huyghens announced the discovery of one satellite of Saturn, and expressed the opinion that the six planets and six satellites then known, and making up the perfect number of twelve, composed the whole of our planetary system. In 1729 an astronomical writer expressed the opinion that there might be other bodies in our system, but that the limit of telescopic power had been reached, and no further discoveries were likely to be made.[A] The orbit of one comet only had been definitively calculated. Since that time the power of the telescope has been indefinitely increased; two primary planets of the first class, ten satellites, and forty-three small planets revolving between Mars and Jupiter, have been discovered, the orbits of six or seven hundred comets, some of brief period, have been ascertained;—and it has been computed, that hundreds of thousands of these mysterious bodies wander through our system. There is no reason to think that all the primary planets, which revolve about the sun, have been discovered. An indefinite increase in the number of asteroids may be anticipated; while outside of Neptune, between our sun and the nearest fixed star, supposing the attraction of the sun to prevail through half the distance, there is room for ten more primary planets succeeding each other at distances increasing in a geometrical ratio. The first of these will, unquestionably, be discovered as soon as the perturbations of Neptune shall have been accurately observed; and with maps of the heavens, on which the smallest telescopic stars are laid down, it may be discovered much sooner.

[A] Memoirs of A.A.S., vol. iii, 275.

THE VASTNESS OF CREATION.

But it is when we turn our observation and our thoughts from our own system, to the systems which lie beyond it in the heavenly spaces, that we approach a more adequate conception of the vastness of creation. All analogy teaches us that the sun which gives light to us is but one of those countless stellar fires which deck the firmament, and that every glittering star in that shining host is the center of a system as vast and as full of subordinate luminaries as our own. Of these suns—centers of planetary systems—thousands are visible to the naked eye, millions are discovered by the telescope. Sir John Herschell, in the account of his operations at the Cape of Good Hope (p. 381) calculates that about five and a half millions of stars are visible enough to be distinctly counted in a twenty-foot reflector, in both hemispheres. He adds, that "the actual number is much greater, there can be little doubt." His illustrious father, estimated on one occasion that 125,000 stars passed through the field of his forty foot reflector in a quarter of an hour. This would give 12,000,000 for the entire circuit of the heavens, in a single telescopic zone; and this estimate was made under the assumption that the nebulæ were masses of luminous matter not yet condensed into suns.

These stupendous calculations, however, form but the first column of the inventory of the universe. Faint white specks are visible, even to the naked eye of a practiced observer in different parts of the heavens. Under high magnifying powers, several thousands of such spots are visible,—no longer however, faint, white specks, but many of them resolved by powerful telescopes into vast aggregations of stars, each of which may, with propriety, be compared with the milky way. Many of these nebulæ, however, resisted the power of Sir Wm. Herschell's great reflector, and were, accordingly, still regarded by him as masses of unformed matter, not yet condensed into suns. This, till a few years since, was, perhaps, the prevailing opinion; and the nebular theory filled a large space in modern astronomical science. But with the increase of instrumental power, especially under the mighty grasp of Lord Rosse's gigantic reflector, and the great refractors at Pulkova and Cambridge, the most irresolvable of these nebulæ have given way; and the better opinion now is, that every one of them is a galaxy, like our own milky way, composed of millions of suns. In other words, we are brought to the bewildering conclusion that thousands of these misty specks, the greater part of them too faint to be seen with the naked eye, are, not each a universe like our solar system, but each a "swarm" of universes of unappreciable magnitude.[A] The mind sinks, overpowered by the contemplation. We repeat the words, but they no longer convey distinct ideas to the understanding.

[A] Humboldt's Cosmos, iii. 41.

CONCEPTIONS OF THE UNIVERSE.

But these conclusions, however vast their comprehension, carry us but another step forward in the realms of sidereal astronomy. A proper motion in space of our sun, and of the fixed stars as we call them, has long been believed to exist. Their vast distances only prevent its being more apparent. The great improvement of instruments of measurement within the last generation has not only established the existence of this motion, but has pointed to the region in the starry vault around which our whole solar and stellar system, with its myriad of attendant planetary worlds, appears to be performing a mighty revolution. If, then, we assume that outside of the system to which we belong and in which our sun is but a star like Aldebaran or Sirius, the different nebulæ of which we have spoken,—thousands of which spot the heavens—constitute a distinct family of universes, we must, following the guide of analogy, attribute to each of them also, beyond all the revolutions of their individual attendant planetary systems, a great revolution, comprehending the whole; while the same course of analogical reasoning would lead us still further onward, and in the last analysis, require us to assume a transcendental connection between all these mighty systems—a universe of universes, circling round in the infinity of space, and preserving its equilibrium by the same laws of mutual attraction which bind the lower worlds together.

It may be thought that conceptions like these are calculated rather to depress than to elevate us in the scale of being; that, banished as he is by these contemplations to a corner of creation, and there reduced to an atom, man sinks to nothingness in this infinity of worlds. But a second thought corrects the impression. These vast contemplations are well calculated to inspire awe, but not abasement. Mind and matter are incommensurable. An immortal soul, even while clothed in "this muddy vesture of decay," is in the eye of God and reason, a purer essence than the brightest sun that lights the depths of heaven. The organized human eye, instinct with life and soul, which, gazing through the telescope, travels up to the cloudy speck in the handle of Orion's sword, and bids it blaze forth into a galaxy as vast as ours, stands higher in the order of being than all that host of luminaries. The intellect of Newton which discovered the law that holds the revolving worlds together, is a nobler work of God than a universe of universes of unthinking matter.