Astronomical Lectures.
By Prof. Orson Pratt.
Lecture First.
Astronomy is that science which treats of the figures, magnitudes, distances, motions, relative positions, appearances, and physical constitutions of the great bodies which compose the viable universe; or, in other words, it is that department of science which has for its object to investigate the phenomena of worlds and systems of worlds, which exist in countless numbers in the immensity of space. It is that science which lifts the veil of obscurity, and exhibits the grand scenery of the universe as it existed in ages past, as it now exists, and, if not interfered with by causes unknown, it will exist in ages to come. It is that science which, above all others, is calculated to give us the most profound, sublime, and exalted views of the power, wisdom, and goodness of that Being who formed those magnificent systems from the eternal elements, and devised laws, calculated to maintain their stability through all their complicated and infinite variety of movements, for indefinite ages to come.
This is a science which has engaged the attention of individuals, nations, and generations from the earliest period of man; for what rational being can look upward into the blue vault of heaven, and behold the sun in its effulgent glory; the moon, shining with a silvery brightness, exhibiting its ever-varying changes; the stars bespangling the vast concave of a nocturnal sky, twinkling, as it were, with joy, and lighting up the dark, unfathomable abyss of an unknown immensity; what rational being, we again enquire, can behold this august and sublime scenery without feeling the most intense desire to know something more about it? Kings upon their thrones, and the humble shepherd in the field, have alike participated in this feeling. The poet, enraptured with the magnificent glories of the heavens, has poured forth his sublimest effusions in the most melting, harmonious strains of glowing eloquence. While the man of God, with loftier views and higher aspirations, has soared aloft from nature up to nature’s Author, and, overpowered with the ideas of the infinite greatness and resplendent glories which surround him on every side, he bows in humble adoration before the Great Eternal, and exclaims, “What is man that thou art mindful of him, or the son of man that thou visitest him?”
Among the early cultivators of this science, the prophet Enoch stands conspicuous before the antediluvian world. This great astronomer ascertained that the sun, moon, and stars were not merely lights placed in the firmament of heaven for the meager purpose of giving light to the inhabitants of this world; but he learned that they were made for a more noble purpose – to accomplish more noble ends; in fine, that they were worlds of themselves; inhabited by rational, intelligent, and moral beings. Neither did he limit the universe to the few shining orbs visible to the naked eye; but while enrapt in the visions of the Spirit, his mind expanded, and the immensity of creation presented itself before him, stretching out to infinity in all directions; and overwhelmed with the magnitude of this magnificent scenery, he gave vent to his feelings in the following beautiful and sublime language: “Were it possible that man could number the particles of the earth, and millions of earths like this, it would not be a beginning to the number of thy creations; and thy curtains are stretched out still; and yet thou art there, and thy bosom is there; and also thou art just; thou art merciful and kind forever; thou hast taken Zion to thine own bosom, from all thy creations, from all eternity to all eternity, and nought but peace, justice and truth, is the habitation of thy throne, and mercy shall go before thy face and have no end.” – [See Prophecy of Enoch, revealed by Joseph Smith, the Seer.]
None of our modern astronomers, though aided by the most powerful telescopes, can take in a more enlarged view of the universe than is here given. He not only declares the immensity of the present universe, but he declares the immensity of unnumbered millions of universes, traced back in almost an endless succession. That these were all habitable worlds is clearly shown from the fact that a people called Zion were taken or redeemed from them all; from which we learn that the great plan of redemption is not limited to our world, nor indeed, to the present universe of worlds; but has been continued in all anterior worlds, from all eternity.
Abraham also, through the Urim and Thummim, enriched the science of astronomy by discovering KOLOB, the grand, presiding, central world among those of the same order in the present universe. It is from the diurnal and annual revolutions of this vast body that God, and the highest orders of celestial intelligences measure their time. Situated comparatively near Kolob, Abraham discovered many other great worlds of the same order, each governing and controlling vast systems of their own, according to the laws and forces which God ordained for those of the same order.
Worlds of a superior order, or those which have ascended higher in the grand scale of progression, are not under the dominion of Kolob; but they constitute that vast assemblage of celestial kingdoms, redeemed in eternal ages past, where Gods, enthroned in majesty, power and might, arrayed in all the gorgeous splendors of celestial light, sway a universal scepter over all. Kolob, and the universe of kingdoms over which it presides, have advanced by degrees, through a long succession of ages, until they have drawn nigh unto the throne of the Eternal; and are waiting, in their turn, to be admitted among the higher order of worlds, under superior laws, and with superior privileges. – [See Book of Abraham, translated by Joseph Smith, the Seer, from Egyptian papyrus, taken from the catacombs of Egypt.]
Moses, like the astronomers who had preceded him, contributed much valuable information in relation to the origin, extent, purpose and final destiny of the present universe. By him we learn concerning the agencies that were engaged in the magnificent work of forming the worlds. By him we learn that the organization of our globe, though but a speck among the vast constellations of heaven, was not done in a moment, but by a succession of laws issued from the mouth of Jehovah; each law taking effect during a certain period called day, or age, gradually arranged the elements, combined them in their proper proportions, and placed them in their proper positions, until it had fulfilled the purpose or end for which it was given, when it gave place to other laws of a higher order, which further organized, arranged and perfected the globe for its future destiny, until at last, after a succession of ages, it is prepared for the habitation of man, and pronounced very good. By him we learn that vast numbers of worlds have already passed away, or their substances have been dissolved into their original elements, and new worlds formed in their place. By him we learn that the end or purpose to be accomplished by the formation of worlds, is the immortality and eternal life of man. By him we learn that the dimensions of the universe are inconceivably great, and that the creations of which it is composed cannot be numbered unto man, but that they are all numbered by Him who made them. __ [See the visions of Moses, revealed anew by Joseph Smith, the Seer.]
It is easy to perceive from these discoveries of Moses, that the universe, however great in the estimation of man, still has its limits or boundaries; it is not infinite; if so, its creations could not, as we conceive, be numbered; but as the Almighty has numbered them, they must be finite. Therefore, there must be an infinity of space where organized worlds do not exist; but as there is no space without a kingdom, [See revelation to Joseph Smith, the Seer] it follows that there must be an infinity of the smaller kingdoms of matter which have not as yet been organized into bodies sufficiently capacious to accommodate rational and intelligent beings like man; and therefore there is an ample sufficiency to enlarge eternally the boundaries of that vast system of worlds now in existence.
Passing over many distinguished and celebrated astronomers of ancient times, we merely observe, that during the dark ages, ignorance usurped its dominion over the mind of man, and the light of ancient astronomy became nearly extinguished from the world; the earth was assumed to be the stationary centre of the universe, around which the sun, moon, and stars were said to perform their revolutions. Eccentrics, cycles and epicycles were invented to account for the irregular motions among the planets; and the whole system of astronomy became encumbered with absurdities invented to uphold the false theories of Ptolemy and Aristotle, which held for many generations an almost universal sway over the mind of man.
Copernicus, at the beginning of the sixteenth century, broke through, in a measure, the superstition and ignorance of his predecessors, by transferring the centre of the planetary system from the earth to the sun, and thus forming the heliocentric theory to account for the phenomena observed – Kepler, nearly a century afterwards, discovered the elliptical theory of the planets, and overturned the favorite hypothesis of circular orbits, which had, up to that time, been universally received. He also discovered the law of motion in elliptical orbits, and unfolded the relation existing between their periodic times and distances.
These grand improvements in the science of astronomy laid the foundation for the great discoveries of the immortal Newton, who revealed to the astonished nations that great law of universal gravitation, or the law of force, by which the great bodies of the universe are bound together in their respective orbits. During the last century and a half, the Newtonian system has been studies with unwearied diligence, and astronomy has been rescued from the errors and absurdities of the dark ages, and established upon the firm foundations of mathematical certainty, which can never be overthrown.
It is the Newtonian system which we shall endeavor to illustrate in the present series of lectures, and to which we earnestly solicit your undivided attention. We shall commence with an examination of the earth as one of the constituents of our solar system, and as the planet with which we are more immediately connected, and as the station from which all the others are seen. If we form erroneous opinions in relation to the earth, the same errors will be interwoven, in a greater or less degree, with all our notions concerning the other bodies of the system. If we suppose the earth to be a flat, extended plane, the phenomena exhibited in the heavens as seen from different points of its surface, would be inexplicable. If we suppose it to be stationary, the motions observed among the heavenly bodies can no longer be considered as apparent, arising from the motion of the earth, but as the real motions of the bodies themselves, many of which would appear inconceivably strange, if not absolutely absurd, being subject to no regular law of order, which characterizes other phenomena with which we are acquainted.
If the rising generation among these mountains were to grow up without any instruction in regard to the form, magnitude, and motions of the earth, only what they should gain by their own observations, their first impression would be that the earth is a kind of concave valley bounded by mountains on every side; and after an exploration of fifty or a hundred miles, their views would be somewhat enlarged; they would now consider the surface of the earth a succession of hills and valleys, delineated upon a comparatively flat plane. All ideas concerning the extent or thickness of this plane would be exceedingly vague and uncertain. Some might suppose it to be limited by an awful precipice extending down through the infinite depths of space. Others might suppose the earth itself an infinitely extended plane without boundaries in any direction except its upper surface.
We will now suppose that a committee should be appointed by them to explore the earth in an eastern direction. When they had traveled due east between seventeen and eighteen thousand miles alternately over land and sea, what would be their astonishment at finding themselves just entering the valley of the Great Salt Lake on the west? . – They would scarcely believe the evidence of their senses. The only just conclusion they could form upon so strange a phenomenon would be that the earth is round, at least from east to west. But a question would immediately arise among them, whether the earth was round or convex in all directions like a ball, or whether it might not be of a cylindrical form, like a saw-log, being convex from east to west, but straight from north to south. This question could be decided in the following manner if we stand on the deck of a ship at sea when out of sight of land, we should be able to see hundreds of miles in all directions, if the surface of the ocean were a level plane; indeed, were our view not obstructed by mists, fogs, or clouds, we should be able to see hundreds of millions of miles; large continents and islands thousands of miles in the distance would be rendered visible. Observation shows this not to be the case; but we find in every direction from our station a clear, well defined boundary only a few miles in the distance. As ships pass over the boundary, we gradually lose sight of them, the hull disappearing first, then the lower sails, and finally the top-sails seem to sink out of sight as they recede in the distance. After they have thus disappeared, the most powerful telescopes will not render them visible; but by ascending to the mast head they seem gradually to rise again above the horizon, and are distinctly visible to the naked eye, which clearly demonstrates that it is not owing to any incapacity of the organs of vision to see further, but that the convexity of the water intervenes between the eye and the object, and thus hides it from our view.
Since the same effects are observed from every part of the ocean, and in every possible direction north and south as well as east and west, it follows that the same convexity must prevail on every side; and therefore that the earth cannot be of a cylindrical form, but must be round like a globe.
Another demonstrative proof that the earth is a globe, is given by considering the form of the earth’s shadow when it falls upon the surface of the moon, during a lunar eclipse. When the moon passes directly behind the earth, so as to form a straight line with the earth and sun, the shadow of the earth, extending in a direction opposite to the sun, will fall upon the moon, and will at all times appear circular upon the moon’s disc. If the earth were considered stationary, and if a lunar eclipse should always happen at the same hour of the night, this would be considered unsatisfactory evidence of its globular figure: for there are many bodies, besides a globe, which will in certain positions cast a circular shadow. A grindstone, a sugar loaf, or even a log of wood, when held with its circular ends facing a light, will form a circular shadow in the opposite direction.
Now in order to determine the true figure of either of these bodies from its shadow, let different sides alternately face the light, and we should soon be able to declare its true figure with mathematical certainty. Now let different sides of the earth be presented towards the sun, and if the shadow still continues to be circular, we know the earth must be a globe, for no other figure is capable of producing a circular shadow when its different sides are exposed to the sun in a variety of positions. For instance, if a lunar eclipse were to happen at six o’clock in the evening about the first of January, and another should happen at some future period about the same time of year, but at 12 o’clock at night; then the side of the earth presented to the sun during the former of these eclipses would be at right angles to the side presented during the latter; yet in both instances its shadow upon the moon would be circular. This, then, is a conclusive demonstration of the globular figure of the earth, independent of its diurnal or annual revolution. But if the diurnal revolution of the earth be admitted, then we shall have almost every side of the earth successively turned towards the sun; and eclipses happening within a comparatively short period of time; under all these conditions.
By such observations as these, the earth is proved to be of a globular form by the most incontrovertible evidence.
When we come to speak of the diurnal revolution of the earth upon its axis, we shall again refer to its figure, and show that there is a slight deviation from the globular form, arising from causes connected with that motion. But for all practical purposes, wherein great nicety or precision is not required, the errors which arise by assuming the earth to be a perfect sphere, will be inappreciable.
Objections have been raised to the globular form of the earth on the ground that the great inequalities existing on its surface under the name of mountains and valleys are inconsistent with such a form; but the highest mountains of our globe, when compared with the earth itself, would be only about one-sixteen hundredth part of its diameter. The roughness on the surface of an orange is far greater, when compared with the magnitude of the orange, than is the roughness of the surface of the globe when compared with its magnitude. Indeed, if our globe were reduced to the size of an orange, the mountains delineated upon its surface, if reduced in the same proportion, would require a microscope of considerable power to clearly discover them.
Having determined that the earth is a globe, we shall next inquire, how its magnitude may be determined. If any means can be devised by which we can measure the circumference of the earth, its diameter, together with the number of square miles upon its surface, and also its solid contents, can be easily calculated. Now to measure the whole circumference of the earth with a chain, or line, or any other accurate measure, would be altogether impracticable on account of mountains, oceans, swamps, and other opposing obstacles. But if we can accurately measure a portion of this circumference, for instance, one degree of latitude, and find how many miles it contains, all that would now be necessary would be to multiply the number of miles in one degree by 360, which is the number of degrees in the whole circumference of the earth, and the product would be the number of miles around the earth. Now a degree may be measured as follows: let the latitude of this Council House be accurately taken by a sextant, then measure due south until you reach the southern extremity of the valley, and again take the latitude, which we will say is one half of a degree, and the distance as measured we will also say is 34 3-4 miles; this doubled, would be 69 1-2 miles, or the length of one degree: this multiplied by 360 would give 25,020 miles for the circumference of the earth; this divided by 3.14159 would give 7964 miles for its diameter. As the average length of a degree is not quite 69 1-2 miles, these numbers are rather too large.
To those who are unaccustomed to traveling, it is difficult to convey a correct idea of the magnitude of the earth in numbers. But as we are now addressing a people who have traveled over no inconsiderable portion of the earth’s circumference, they will be better prepared to form more correct notions on this subject, by comparing the distances over which they have traveled with the numbers expressing the distances around and through the earth. The distance from this to Council Bluffs, is, in round numbers, about 1000 miles. The diameter of the earth is nearly eight times that distance; while the circumference is nearly twenty-five times that measure. If we were to pass round the earth with our ox teams at the rate of 10 miles per day, it would require about 7 years to perform the journey. But, (as will be more fully noticed here after) this magnitude, vast as it may appear, dwindles into insignificance, when compared with the sun and many of the other stupendous bodies of our system.
Having determined that the earth is a globe of definite magnitude, the next question which would naturally occur is, upon what does it rest? Has it any solid foundations? These questions naturally arise, from the constant habit which we have of associating foundations with all the objects perceived upon the surface of the earth. Without some kind of support, all terrestrial objects have a constant tendency to fall perpendicularly to this surface. We have never seen any exceptions to this general law, and therefore, when we think of the earth as a whole, we naturally suppose that it must fall unless supported by something; but a few moments of reflection will convince us that the force, whatever it may be, which causes all objects to fall or press towards the centre of the earth, will have no tendency to cause the earth as a whole to move in any direction. Forces which press equally and in opposite directions will be in equilibrium, and cannot produce motion.
If the forces of any two opposite hemispheres of the earth, taken in any position, be equal, as they are in opposite directions, they cannot produce motion; therefore the earth, under such forces, existing within itself, will have no tendency to go in one direction more than in another. Hence, unless it were influenced by bodies external to itself, it would remain at perfect rest in any part of space where it might be placed.
The earth, under these conditions, would have no up nor down, relative to the different points of space with which it is surrounded. Up and down are relative terms, and when applied to the earth, magnify from and to its centre. It will easily be perceived that the earth could not fall down towards its own centre, so as to alter the position of that centre in space; neither could it as a whole move from that centre in any possible direction. Because we see a wooden globe have an upper and under side relatively to the earth in any given position in which it may be placed, we are apt to transfer the same property to the earth, and suppose it to have an upper and under side in relation to the space enclosing it; but this is an illusion, formed by habit, which we must entirely divest ourselves of, in order to form correct ideas of the earth existing in space without foundations on which to rest. If any one of this audience were placed alone in empty space, and no other bodies existed, we could not conceive of up or down. As he would have no tendency to move in any direction; the terms over, under, above, below, &e., would have no meaning whatever to him. If he were to take a bushel of wheat and sow it in every possible direction, he never could lose one kernel of it, for by the power of gravity, it would all return to him again with the same velocity with which it was projected or scattered from him. If he were to fire a bullet directly from him, though it would be absent for many hundreds of years, and pass over many thousands of miles in space, yet it would return and penetrate his body, having the same velocity it had when first projected from the mouth of the gun. The direction of the bullet or of the kernels of wheat would be up or down as they proceeded from or towards the body.
Our antipodes, or the inhabitants of Desolation and Amsterdam islands, situated in the Indian Ocean, are on the opposite side of us; their feet point towards ours; their zenith, or that portion of the sky which is over their heads, is directly under our feet, and yet they have no more tendency to fall towards their sky than we have towards ours; all bodies around them have the same tendency to press towards the surface of the globe there, that they have here; the Indian Ocean is no more likely to be poured out into their sky, than the Salt Lake is into ours. Magnets, placed on opposite sides of an iron globe will adhere to its surface and will revolve with it without falling. A powerful magnet held 2 or 3 inches from the under surface of an iron globe, will fall upward to that surface, the same as a stone will fall downwards upon the surface of the globe of the earth. All directions towards the centre of an iron globe are down to a magnet; all directions from its centre are up. All who wish to make any progress in astronomy must familiarize their minds with the right conception of up and down, ascending and descending, above, below, and such like terms, always remembering that they are terms which relate only to the centre of forces, and that they change their directions as often as we change the position of objects in relation to that centre.
[Transcribed by Erin T. McAllister,Christina J. Durham, and Mauri Pratt; May 2012]
Orson Pratt. “Astronomical Lectures: Lecture First”, Unknown newspaper, 27 December 1851.