rV h Origin of our Planetary System Br EUGENE MILLER, A. M. BY THE SAME AUTHOR Secret of the Universe. Gravity- its Origin and Nature $1.60, Post Paid CRANE 85 COMPANY TOPEKA, KANSAS Trom "A New Philo«op1iy and its Author," by LilKaa W'liiting in The InUrnahoiMl Psychic Gazette of London: "Few themes totild be mca-e alluring than that of pos- sibly surprising the fcotution -of the mystery of this vast universe iB -Bhich vre find ourselves; and if Pi-ofo^or Eugene Miller, of Kansas Citj, U. ft. A., who -has just issued a book with fhib title, Jia-s succeeded in '^phicking out the heart of the mysterj-,' his readers will he indebted t-o him, as they will surely be thrrfleji and interested by his discovery. Piofessor Miller is enfitted to attention because he has a constructive philoSdjrfr. . "TThether or not the reader shall accept Professor Mil- , ler's conclusions, there can be no question as to ihe valfie of the book in the extremely intere>ting and important problems that it suggests, and m its thus inciting new mental activities. iVs students of the entire phenomena of life, phjsiral and psychical, the two so strangelj' in- terpenetrhted at manj-- points,, new outlooks ip, science are invaluable to us all." {See third page of coier) • With the Compliments o. .lie Author. THE ORIGIN OF OUR PLANETARY SYSTEM BY EUGENE MILLER, A. M. AUTHOR OF The Secret of the Umverse. Gravity-Its Origin and Nature PRICE BO CENTS (POST PAID) CbANP & COMPANT, PUBUSHBBS ToPEKA, Kansas Copyright, 1918, by MaEIB V. MlUiEK. ArFECTIONATBLT DEDICATED TO MT Children mulitr 1^. MxlUx, m.S. Miss (Sltesaa MUIbv The Origin of our Planetary System Cornell University Library The original of tliis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924031323938 PREFACE. Some time ago a distinguished engineer was asked for his opinion upon a radical departure in mechanics which, if successful, would prove a tre- mendous step in advance of any previous achieve- ment. His reply was: "No engineers ever were able to venture so far on unknown ground and get perfect results immediately." It is not difficult to apply his answer to the effort set forth in the following pages. Effort it is, and I do not doubt but the perfection of de- tails shall come later, and, possibly, from an abler pen than mine. Fortunately or unfortunately, I have been a pioneer in spirit all my life. I have not been content blindly to follow beaten paths. But pio- neering is costly, and it is seldom that he who essays to play the role reaps any tangible benefit. However, if he is a man of vision he sees distant (7) 8 PREFACE. scenes that do not come within the range of con- servative eyes ; objects and purposes to him are present long before many of his generation are familiar with the terms in which he thinks. Too often he gesticulates before stoUd faces and ap- peals to ears that are closed to all except the ap- parent needs of the immediate present. Some- times, irritated by an irresponsive environment, he frets when his contemporaries continue to delve so deep in those cruder purposes, born of present wants ; but in his saner moments he re- grets his impatience, pushes his earUer visions to the background, and behold, he sees another— a vision which discloses the teeming world of muscle and mind struggMng to lay the foundation for a future wider than today and deeper than tomor- row. It is a goodly vision. When, at times, the curtain has lifted and I saw this picture of the future, I longed to join hands with the humblest worker who was doing his part in this creative construction and include my contributive effort in the great sum total. This is why I have set this little book out upon its hazardous journey, with due appreciation of PREFACE. 9 the accomplishments of the past and the efforts of the present. Apologies are out of order, and fear ill becomes the pioneer ; but the human bond still lives, and naturally I am interested in what you may think about this voyage of discovery. I shall be pleased to have you express yoiu- opinion. For if the theory herein set forth is right, it means much ; and this "much" will become common property. But if this theory is wrong, it means only the mistake of the one who evolved it. EUGENE MILLER. 743 Lafayette Avenue, Kansas City, Kansas. The Origin of our Planetary System The announcement of a subject like this will produce different effects upon different people. Those who are well informed in regard to the his- tory and results of efforts to solve this great prob- lem will elevate their eyebrows and smile at the utter rashness of the individual who proposes to do what some of the world's most profound minds have failed to accompUsh. And there is a second class, a very large class, who have heard of the Nebula Hypothesis, and in a general way have considered that the origin of our system is fully accounted for by this great creation of Laplace. I am satisfied that the most of those who be- long in the first class are inclined to the belief that the final solution of the problem is impossible. As an illustration of this view of the matter, let (n) 12 OEIGIN OF OUR PLANETARY SYSTEM. me quote Sir Robert Ball, one of the most distin- guished astronomers of our time. On page 530 of his "Story of the Heavens" he makes this state- ment : "The actual steps of the process by which the primeval nebula became transformed into the solar system seem to lie beyond reach of discov- ery." In 1890 Prof. Newcomb wrote to Dr. T. J. J. See as follows : "Your interest in the origin of the heavenly bodies is a very natural one, but I have httle hope that any of these problems can be settled in our time. I have formerly given much attention to these questions myself, but have found the whole subject so unsatisfactory that I have entirely given it up." Dr. See gives this let- ter in his "Researches on the Evolution of the Stellar System." This seems to be the prevailing opinion among astronomers. And if I were asked to give my opinion in regard to the universal fail- ure to solve this great problem I should without a moment's hesitation say that it was due to the lack of a proper analysis of the solar system as it presents itself to us today. It is impossible to solve any great problem unless you can first make the correct analysis as it lies before you; and a ORIGIN OF OUR PLANETARY SYSTEM. 13 man may hit upon this analysis in a purely acci- dental way, as has been illustrated time and time again in the history of scientific progress. And it does not follow that great minds are discredited because a mind not so great happened upon the right analysis and solved the problem. Now for the benefit of those who supposed that this problem had already been solved, I shall quote from the eleventh edition of the Encyclopedia Britannica, Vol. 19, page 333. Under the head- ing of "The Nebula Hypothesis," Sir Robert Ball writes: "A theory advanced to account for the origin of the solar system. It is emphatically a speculation ; it can not be demonstrated by obser- vation or estabhshed by mathematical calculation. Yet the boldness and the splendor of the nebular theory have always given it a dignity not usually attached to a doctrine which from the very nature of the case can have but little direct evidence in its favor." The expression "solar system" necessarily in- cludes the sun, but I shall confine myself strictly to the origin of the planets and their associates, 14 OEIGIN OF OTJR PLANETART SYSTEM. and if I succeed in solving this restricted problem I shall accomplish no mean task. I do not deem it necessary to criticise in detail the various theories that have in time past been proposed for the explanation of our planetary sys- tem. From the quotations that I have just given it is quite clear that, so far, no theory has been propounded which has proven satisfactory in de- tail; no theory has yet been offered which was self-demonstrating, nor has any theory been able, as it develops step by step, so to emphasize its con- formity to well known principles as to furnish a check upon its correctness. If I can provide a theory that will furnish its own checks as to its correctness I believe that I shall render a real serv- ice to the world both in the present and in the fu- ture. In the first place, let me state that I am going to approach the problem just as I would any other puzzle. Right at the beginning I want to know just exactly what I have got to do ; and knowing that, I shall by searching analysis endeavor to find a reference point, a logical center from which I may work outward in all directions as I take up ORIGIN OP OUR PLANETARY SYSTEM. 15 each one of the detailed parts of the problem. And the mere statement in detail of the requirements of the problem may prove of great assistance in my effort to locate, through analysis, this very essen- tial point of reference. What the specific requirements of the problem are I shall state at the very outset, so that the reader may have no difficulty in checking up the argument item by item as the theory unfolds be- fore him. These requirements comprise the as- certained facts which the theory must explain, and to which the theory must conform before it can expect to appeal to any critical intelligence. In some theories the material necessary was drawn from indefinite space, or from a purely imaginary primordial shell, it accumulated in definite places for most indefinite reasons. Knowing the in- definiteness that has characterized theories of the past, I must insist on definite and specific details ; I must not require that matter shaU stage any per- formances during the evolution of our planets which it would not repeat today under identical conditions. Bearing in mind these statements, read now the requirements. 16 ORIGIN OF OUR PLANETARY SYSTEM. The Requirements of the Problem: (1) We have learned that all the known planets revolve around the sun in very nearly the same plane. No theory can be accepted unless it ex- plains this particular point. (2) All the known planets revolve in the same direction about the sun. The true theory must explain this. (3) The known planets are divided into two groups with reference to size. We must be able to teU why a small planet was formed in one in- stance and a large one in another instance. A haphazard explanation or guesswork will not do here. (4) Small planets occupy the space between the sun and Jupiter. But going outward from this region of small planets, we find that within the limits of our present knowledge there is noth- ing but planets of monster proportions. On one side of a given point we have only small planets ; on the other side of that point we have nothing but large planets. This grouping of the planets with respect to size is more than peculiar, it is re- markable, and insistently calls for an explanation. ORIGIN OF OUR PLANETARY SYSTEM. 17 (5) Conunencing at Jupiter and going toward the sun, the planets show a considerable increase in size until we reach the earth, and then an almost equally remarkable decrease in size for the rest of the way. But on the other side, when we go from Jupiter outward, there seems to be a con- tinuous decrease in size, or a tendency to decrease in size. (6) Commencing at Jupiter and going toward the sun, the specific gravity increases from Mars to the earth, where it touches the maximum, and then decreases to Mercury. Graphically the vol- vmae curve and the specific gravity curve are very similar for the inner planets. On the outside of Jupiter the specific gravity shows an almost regu- lar tendency to increase as we go outward. But more remarkable still, we find aU the in- terior planets have a high specific gravity, and aU the outside planets have a low specific gravity. Here is quite a complex requirement. (7) Between the sun and Jupiter is a region that may be called the region of the minimum number of satelUtes, and from Jupiter outward to the present known limits of our system is a region 18 ORIGIN OF OUR PLANETARY SYSTEM. that we may call the region of maximuin number of sateUites. Possibly this may be explained, at least in part. (8) Roughly speaking, the distances of the plan- ets are arranged, with reference to the sun, in ac- cordance with a certain series of numbers as set forth in what is known as "Bode's law." So far, I can not recall that any extant theory even at- tempts to tell why any given planet should be formed at one place or at any given distance from a given center rather than at another place or at any other distance from a given center. There ought to be some reason at least for what Bode's law tried to formulate. (9) All planets rotate on their axes now, or at some time in the past did rotate on their axes. In all cases where the rotation continues, the mo- tion is in the same direct way, with possibly two known exceptions. I say "possibly" two excep- tions, because in the case where this motion is retrograde it may not be an exception but simply a variation of the law. There is a difference be- tween an exception to a law and a variation of a law. This imanimity of rotation should be ex- OKIGIN OF OTJK PLANETARY SYSTEM. 19 plained. Probably it would be well to include under this head the revolution of satellites around their primaries, which also is direct except in a few marked instances. (10) Any theory is incomplete which fails to explain comets and their remarkable orbits, which show — (a) Marked eccentricities, and (&) A great variety of incUnations to the ecliptic. And it must not be forgotten that these comets occur — (c) As single individuals, (d) In groups, and (e) In famiUes. The origia of comets under these limitations cannot be overlooked in any theory that claims to be rational. (11) The correct theory should show the rela- tive age of each planet without any exception. (12) The correct theory should show exactly how many planets there are. In fact, it should show how many there must be, and with equal au- 20 ORIGIN OF OUR PLANETARY SYSTEM. thority declare that there can be no more than that specific number. Here are twelve specific requirements which must be considered seriously in any attempt to discover the origin of our planets. In former times people took appearances for realities and de- clared that the earth was the center of the system ; but later the center was moved to the sun. The sun being the center of mass, it was only natural that later thinkers in their efforts to solve the rid- dle of origin should assume the sun as a center from which to reason in regard to this origin. But it does not always follow that the center of mass is the same as the center of reference from which we should reason when we come to seek out the origin of the various members of a system. Examine, if you please, the twelve requirements, and note that requirements (3) and (4) indicate that Jupiter stands between the group of small planets and the group of large planets, using Jupiter as a marker and considering him in a class by himself, which is perfectly natural, for there is none to compare with Jupiter either in size or mass. ORIGIN OF OUR PLANETARY SYSTEM. 21 In (5) we see that Jupiter is a pivotal point, not onljr with reference to size but with reference to change in size. From Jupiter toward the sun there is a gradual rise in size from asteroid to the earth, and then a decline to Mercury. The point is that this series in sizes commences at Jupiter and proceeds with its variation from Jupiter. On the other side of Jupiter commences another series of sizes, from large to small, with much less varia- tion than appears in the interior series. What- ever the relationship of these two series of sizes Jupiter undoubtedly stands between the two, and must in some way be related to both of them. Considering (6), we see that Jupiter seems to be a dividing point with reference to specific gravity. As a class the small, interior planets are of high specific gravity, running from 3.92 for Mars to 5.55 for the earth. On the other side of Jupiter the specific gravity of the planets is quite low, running from .72 for Saturn to 1.22 for Uranus. Besides this particular classification with refer- ence to Jupiter, there seems to be a tendency for the specific gravity to become greater as we go from Jupiter toward the sun, and in like manner 22 OEIGIN OF OUR PLANETARY SYSTEM. the same tendency as we go outward from Jupiter. For the convenience of the reader I copy here the figures given for the specific gravity of each by the late Dr. C. A. Young. Note that the specific gravity of the earth would be a shade less if the moon (according to Prof. Darwin), with specific gravity of 3.39, had not separated from the earth, and possibly several shades less, for the moon likely carried away great volumes of gaseous mat- ter which it has since lost. Here are the figures : Mercury, sp. gr 4.7 (7) Venus, " 4.94 Earth, " 5.55 Mars, " 3.92 Jupiter, " 1.32 Saturn, " 0.72 Uranus, " 1.22 *Neptune, " 1.11 * Fortunately I am able to give the very latest figures as to the specific gravity of the planets. These figures are from Dr. F. R. Moulton's "Intro- duction to Astronomy," issued by the MacMillan Company : Mercury, ap.gr 4 . 48 (?) Venus, " 4.85 (?) Earth, " 5.53 Mars, " 3.58 Jupiter, " 1 . 25 Saturn, " 0.63 Uranus, " 1 . 44 Neptune, " 1 . 09 These values, you will notice, do not change the relative position of any planet in the gravity list. Hence these more recent figures do not require me to change tny argument in any detail, and may be substituted, without a single bitch, for the values given in the text above. ORIGIN OF OUR PLANETARY SYSTEM. 23 In the case of Mercury, its specific gravity was formerly stated as about 7 by other astronomers, although it had the implication of doubtfulness expressed by the interrogation mark as above. Now an examination of these figures will show the two points that I wish to make, namely, that the group on one side of Jupiter shows a high specific gravity and the group on the other side of Jupiter shows a low specific gravity; and also that in each one of these groups the specific gravity tends to increase from Jupiter. In this latter case, no- tice that for the interior planets the specific grav- ity runs from 3.92 for Mars, to 4.7 for Mercury. In the case of the exterior planets, it runs from 0.72 for Saturn, to 1.22 for Uranus, and 1.11 for Neptune. Mark you now, I do not say this increase of gravity is regular as we get farther away from Jupiter going either way, but that there is a decided tendency in that direction. For instance, Mars is nearest to Jupiter, and of all the interior planets its specific gravity is least, and Saturn, the nearest exterior planet to Jupiter, has a lower specific gravity than either Uranus or Neptune. Whatever these comparisons may mean. 24 ORIGIN OF OUR PLANETARY SYSTEM. you can readily see that they give me two sugges- tions to the effect that Jupiter may be a point of reference when we come to consider the constitu- tion of the system. This idea of Jupiter being a point of reference is reinforced by the suggestions in (3), (4) and (5). And I do not beheve that the circumstances from which I deduce this idea are mere coincidences. There is too much of the ap- pearance of law about these circumstances to allow them to be set aside until I have endeavored to test the matter a httle further. I beheve, then, that I am justified in assuming that Jupiter is an important poiut of reference in the very constitution of our system, a center from which to start an investigation about the origin of our planets. Now we know that others in their endeavors to solve this same problem have started with the sun. They made it the center of reference simply be- cause they were carried away with the obvious, and failed to analyze the planetary system and discover a real center of reference. So I am going to set the sun aside, in a measure, and call Jupiter to the witness stand, and see if I can make him tell OBIGIN OF OUR PLANETARY SYSTEM. 25 any better story than my predecessors have been able to extract from his majesty the sun. I shall have use for the sun in his proper place, and in re- moving the sun from the position of supreme cen- ter of reference there may be some consolation to him in the fact that the one who shall take his place shows many of the characteristics of a real sun, and that he never was a planet. But what- ever he is, I shall try to ascertain his true relation to the system of which we know he is a part. The question now before us is this : Is there any astronomical situation or arrangement that could possibly produce our system of planets, emphasize the idea that Jupiter is a permanent reference point, and yet, withal, be so simple as to furnish an automatic proof of its truth step by step as the plan unfolds? Let us see. Well, to start the matter let me say that Jupiter has many characteristics of a sun. At least, its enormous size almost prohibits it being classed as a planet. And if it has now many characteristics of a sun it is possible that these sun characteristics were more numerous and more pronounced some- where in the past. If, then, we refuse to classify 26 OBIGIN OF OUR PLANETARY SYSTEM. Jupiter as simply a big planet, we are forced to consider Tiim as a companion sun to owe recognized Sim at the center of owr system. And it follows from this that our sun was at one time a double star, and is to all intents and purposes still a double star. There is nothing surprising about this, for double and multiple stars are extremely comGtnon in the heavens, and their number grows still greater as investigation proceeds. If oiu* sun was a double star it must have been under double- star law. Let me state one of the important laws in such a case. After making an exhaustive in- quiry in regard to the orbits of a number of double- star systems, Dr. T. J. J. See, in his "Researches on the Evolution of the SteUar System," volmne 1, page 251, draws this conclusion: "It follows, therefore, that the average eccentricity among the double stars is more than twelve times that found in the planetary system, and this extraordinary result is manifestly the expression of a funda- mental law of nature." Leaving out of consider- ation the orbits of comets, which he evidently did not include in the above statement, there is noth- ing in our system which has an eccentricity at all ORIGIN OF OUR PLANETARY SYSTEM. 27 comparable with the eccentricity of the general run of double-star systems. Now, if Jupiter and the sun are components of a binary system there must have been a time when they had this eccen- tricity of orbit. And we know that in some cases orbits are changed from a curve of a given eccen- tricity to another curve of greater or less eccentric- ity, as the case may be. If Jupiter was a companion sun, whatever its origin, whatever its initial proximity to the sun, if it was not already revolving in a very eccentric orbit, sooner or later the results of tidal influence would have compelled it to adopt that particular kind of orbit, for it is agreed that tidal influences are responsible for the eccentric orbits of double stars. When Jupiter, under the repeUing influence of the tides, began to elongate its orbit it was abso- lutely necessary that the two foci should move away from each other along the major axis, and since the sun occupied one focus that focus was practically fixed. So all the moving must have been done by the apheUon focus. This means that the elongation must have taken place mainly 28 ORIGIN OF OXJE PLANETARY SYSTEM. on the aphelion end of the curve, with compara- tively httle elongation at periheUon. It is possi- ble, too, that Jupiter was very near the sun at perihelion when this elongation of its orbit com- menced, and this would allow room for the subse- quent alterations to take place without taking Jupiter's perihehon any very great distance further away. The title of this article precludes any inquiry into the origin of the sun, so I may assume the existence of the sun, or the original nebula from which Laplace evolved the sun. This I can do without conmiitting myself to the defense of the nebula of Laplace. If the sun and Jupiter were ever associated in a single nebula of course we know that Jupiter was at one time in contact with the svm. But be that as it may, with Jupiter mov- ing in a very eccentric orbit with periheUon very near the sun, Jupiter's great seas of molten metal would be subjected to immense tidal oscillations, which sooner or later would produce a tidal rup- ture. The great protuberance of molten metal on the side next the sun would be torn off and dragged with terrific force into the space between ORIGIN OF OUR PLANETARY SYSTEM. 29 Jupiter and the sun, where it would estabUsh itself in an independent orbit as the first-born planet of our system. Mark this point as the beginning of our planetary system. And it is well to bear in mind that there are several conditions that might have hastened the tidal climax. One in particular is the speed with which the ruptured body rotates on its axis. Jupiter rotates very rapidly now, and it is more than probable that it had at that time a very rapid axial rotation. Now at the moment that the attractive power of the sun tore this molten mass from the face of Jupiter there followed the most terrific disturb- ance that had ever occurred in the history of Ju- piter. There was a tremendous reaction. The recoil of the material that had almost left with the departing planet, the rush of molten matter back and forth at the point of rupture, would pro- duce giant oscillations whose force would be added to the already intense tidal disturbances, and whose energy would tend to raise the temperature of the already molten Jupiter. AU this would aid in the second act of this great drama staged in the depths of the universe. 30 OEIGIN OF OUR PLANETABT SYSTEM. We know that tides occur in pairs. When the sun raised a tide on one side of Jupiter, another tide always occurred on the opposite side of that globe. Since we know that this is the rule, it must have been so in the case we are considering. The sun was pulling the great body of Jupiter away from the superficial matter on the opposite side of the planet, and thus raised a great tide on that side. When the tidal oscillations, enormously re- inforced by the reaction from the preceding rup- ture, reached a climax, another planet popped off the side of Jupiter that was turned away from the sun. Here, then, was born the second planet of our system, but from the side of Jupiter opposite the point where the first planet broke away. This is in accord with the recognized procedure in the case of tidal rupture. Our planets, then, were bom as twins; one leaving the parent body to revolve in a smaller orbit, the other separating from the outer side of the parent body to revolve in an orbit outside of the parent body's orbit. The main portion of Jupiter, having been pulled away from the second planet, wiU change its orbit to one much less eccentric. It is impossible to ORIGIN OF OUR PLANETARY SYSTEM. 31 separate great masses of molten metal in a gentle manner. Always there will be liberated forces of inconceivable magnitude. Deep down in the bowels of a great molten body, thousands of miles beneath the surface, there he possibihties of ex- plosion that can not be grasped by the human mind. When the actual separation occurs, these immense explosions, reacting upon the separating bodies, will undoubtedly drive the main body in toward the sun and the outer away from the sun.* It is not difficult to see that when the second planet is born a change comes over Jupiter, and it will begin to return toward that orbit which it used before the culmination of tidal influences had driven it to such hmits of eccentricity. And at each succeeding birth of an outer planet this tendency to resume a more circular orbit will be * Notice that Jupiter's orbital speed was always greater at perihelion. And -this speed was greater at the birth of the first outside planet than it was at the birth of any subsequent outside planet, because this perihelion distance became successively greater at the birth of each subsequent outside planet. This would give the first outside planet a greater tangential fiing than the second, and the second a greater fling than the third, and so on throughout the entire series. This is due to the law of "equal areas in equal times," which applies to every elliptical orbit. This will help to explain the statement that the dis- tances of the outside planets depend largely upon the properties of the ellipse. This statement occurs elsewhere in the text. 32 ORIGIN OF OtTB PLANETARY SYSTEM. illiistrated. But as the tendency to shift its orbit develops, we see that the foci begin to approach each other, and, since the sun occupies one focus and is relatively stationary, aU the moving must be done by the other focus. The greater part of the change will be in the apheUon part of the orbit. Yet there will be a change iu the perihehon por- tion of the orbit, but by no means so great as the change in the aphelion portion. At least one rea- son for the change in the perihehon portion hes in the fact that when the orbit is shortened by cutting comers in the aphehon portion, the moving body travels nearer the sun and is compelled to increase its speed in its orbit, which will of necessity carry it to a greater perihehon distance ; but the perihehon gain wiU be nothing like the loss in the aphehon distance. You wiU readily see that when the next pair of twins is bom that the distance between the two inside planets wiU be far less than the distance between the two outside planets. In the case of the inside planet, when it is sepa- rated from the parent body it wiU approach the sun, or fall toward the sun, and the nearness of its approach to the sun will depend very largely upon ORIGIN OF OUR PLANETARY SYSTEM. 33 its distance from the sun at the moment of sepa- ration and its orbital speed at that time. Let me stick a pin right here. Just a Uttle thought at this point will enable us to understand why the distances between the inner planets are so much less than the distances that separate the outer planets. And so at each tidal rupture the main body swings in nearer the sun on its aphelion jour- ney, thereby increasing its orbital speed. And this increase of orbital speed will of necessity carry it to a greater perihehon distance, making it com- pulsory that it drop each inside planet a little further away from the sun than the preceding in- side planet. And the shortening of the aphelion part of the orbit makes it compulsory that each outside planet travel much nearer the sun than did the preceding outside planet.* What Bode's law attempts to formulate begins to clear up. But I may have something more to say on this matter before I am through. It is perfectly clear now that when planets origi- nate in this way that each planet is born nearly in the plane of the radius vector, in the plane of the orbit of the parent body ; and since they are *See foot note on page 31. 34 ORIGIN OF OXJE PLANETARY SYSTEM. all bom from the same parent body, under like conditions, aU of our planets must revolve about the sun in the same plane, or very nearly the same plane. I say "very nearly," because in each case there will be injected certain coefficients of vis- cosity, explosion, synchronism of various undu- lations and other variable items that will shift the orbital planes more or less. But this theory, so far, will satisfy the demands of requirement (1), for it teUs you not only why the planets revolve in the same plane, but it teUs you that they must revolve in the same plane. Now turn to requirement (2) and see if it is not equally clear why aU the planets have the same direct motion as they travel around the sun. It could not be otherwise, because the motion of the body from which they were born controls abso- lutely the direction of the revolution of each par- ticular offspring. Now let me address myself to requirement (3). Why are the interior planets so small and the ex- terior planets so large? Can this theory explain this point? We'll try it. Let me call your attention to the shape a molten ORIGIN OF OUR PLANETARY SYSTEM. 35 body will assume under tidal influence. As I have remarked already, when a tide is raised on one side of a body there is also at the same time a tide on the opposite side of that body. Now the side on which the tide is raised toward the sun will suffer a greater distortion than the opposite side. As long as there are no obstructions the tide on the near side will be much higher than that on the far side. In fact, the shape of the body will be far from spherical if the body is molten. It will be distinctly ovoid in shape, with the small, sharp end pointing almost directly toward the body which raises the tide, and the round, blunt end pointing in the opposite direction, away from the tide- raising body. Now when the crisis arrives in the oscillation, and the rupture takes place, it will be the apex of the sharp end that will break off on the inside, and the round, blunt end on the out- side. So there will be a small planet for the inside and a great round monster for the outside. But there is another item here that must not be over- looked. I had occasion a little while ago to call attention to the great reaction that took place after the rupture of the first inside planet from the 36 ORIGIN OP OUR PLANETARY SYSTEM. parent body. This reaction increased immensely the oscillation of the molten matter, and it is this greater force that acts upon the rounded tidal wave and breaks off many times the mass of matter that was broken off on the inside, pointed tidal wave. In the case of the outer rupture there is many times the force available for producing the rupture, and the form of the outside wave is con- ducive to contributing a much larger mass to form the outside planet. Besides, we must not overlook the fact that in the case of this outside rupture the sim is puUing the great bulk of Jupiter away from the tidal wave, and that the reinforced oscil- lations which are assisting in the making of the rupture are operating behind the main tidal wave and, as it were, applying their forces in the form of a push at the base of the tidal wave, so that a much larger mass of matter will be driven off than would be driven off if the forces were appUed mainly in the form of a pull appUed at the crest of the wave. The bottom in this case was lifted toward the crest, and hence the plane of separation would occur farther from the crest and nearer the base of the wave than in the case of the rupture on the side ORIGIN OF OUR PLANETARY SYSTEM. 37 toward the sun where the main force is a pull ap- pUed at the crest of the wave and without any such reinforcing oscillations as appeared at the birth of each exterior planet. Can you accept this reasoning as satisfaction in fuU for the requirement (3)? In my humble opinion it suffices. Now since the small planet is always detached from the parent body on the side toward the sun, all the small planets will be found between the parent body and the sun. And since all the big rounded ends are detached from the parent body on the side turned away from the sun, all the great planets will be found on the outside of the orbit of the parent body, just exactly as we find the giant planets outside and never inside the orbit of the parent body, Jupiter. Now read requirement (4) and see if these last remarks do not fuUy and com- pletely explain why all interior planets are smaU and all the exterior planets are giants. In answering the requirements (3) and (4), it is apparent that these two requirements are very closely associated and in a measure overlap each other. It is not surprising to find this condition, 38 ORIGIN OF OUR PLANETARY SYSTEM. and we may find it in several instances in this in- vestigation. In the statement of requirement (5) our atten- tion is called to the fact that the planets, in going from Jupiter to the sun, show a tendency to in- crease in size, from the smallest planets we know, the asteroids, to the earth, which is the largest planet on the inside of Jupiter's orbit. Then for some reason the next planet, Venus, is smaller than the earth, and the next, INIercury, is much smaller than Venus. If we represent the scale of sizes by a curve, the hne will start ahnost at zero to represent the asteroids, rise rapidly to represent Mars, and reach its highest point in portrajdng the size of the earth, then turn downward a Mttle for Venus, and much more for ]\Iercury. Our earth seems to be at a maximum both in size and specific gravity among the interior planets. This is admittedly a difficult matter to explain, and so far as I know it has not even been attempted ; but I have made an effort, and here is the result. On the other side of Jupiter there is less comph- cation as to size. Saturn by aU odds is the largest, Uranus very much smaller, and Neptune is by ORIGIN OF OtJR PLANETARY SYSTEM. 39 some authorities put down as a little smaller than Uranus, and by others as a little larger. However, there is not on this outer side of Jupiter the same irregularity that we find on the inner side. At least, there is a most decided tendency for the outside planets to become smaller the farther we get away from Jupiter ; and it would not be of any great consequence if we found an exception or two no more marked than the possible difference, either way you might take it, between the sizes of Neptune and Uranus. And it will appear later that there entered into the volume problem of these outer planets causes and modifications of causes that in no wise appeared in the volume problem of the interior planets. Bearing these remarks in mind, we may look for the laws gov- erning the volume of the inner planets, and be less hable to become confused. Mercury, according to this theory, was the first born of all the planets. It was pulled from the side of Jupiter that was turned toward the sun, and at the moment when the pull of the sun and the force of the oscillation were sufficient to over- come the gravity and cohesion of Jupiter. And 40 ORIGIX OF OUR PLANETARY SYSTEM. since it follows that the agitation of the surface material of Jupiter at this particular time, and the agitation of the surface at the births of later plan- ets and in the interim between these births, must have raised the temperature on Jupiter, and must have promoted a more perfect fusion, then when ^lercury was bom the state of fusion was not as far advanced as it must have been at a subsequent time. This would mean that the cohesive prop- erties of Jupiter's surface materials would limit the height of the tides, and would offer a greater resistance to any force that was trjdng to cause a tidal rupture, which in turn would mean that the first planet pulled away would be small — at least it would be smaller than it would have been had the surface materials of Jupiter been rendered more mobile and less cohesive by a more advanced state of fusion. And following up this idea of advance in fusion, the next planet should be of larger volume. The next planet is of larger vol- ume, and, other things being equal, the planets of later birth should show a progressive increase in size. This rule of increase in size does go as far as to include the earth, but from the earth on to- OKIGIN OF OUR PLANETARY SYSTEM. 41 ward Jupiter it seems that "other things" are not "equal" ; for there is rapid descent in the volume curve for the rest of the way. Why should the size culminate at the earth and then rapidly de- chne? We must remember that the main force which started and maintained this superficial ac- tivity on Jupiter was the gravity pull of the sun, and that this particular tide was raised by the di- rect pull of the sun, and that after the birth of each planet Jupiter went on past its perihelion region toward its apheUon, swinging in nearer to the sun in that region, and then as a matter of necessity when it retiu-ned to the perihelion, by reason of its increased velocity it moved farther away from the sun. Now, gravity depends upon two things; one is the square of the distance and the other is the mass. Now, at each planet-producing rupture Jupiter is farther away from the sun,* and the gravity force of the sun is less at each one of these occasions than it was at the preceding occasion, but to offset this decrease of gravity pull of the sun * The reader must understand that the tidal ruptures are supposed to take place on the perihelion end of Jupiter's orbit, and this part of the orbit ia being lengthened after each rupture. Jupiter is moving farther away from the sun on this end of the orbit. 42 ORIGIX OF Otm PLAXETAKY STSTEil. the state of fusion on Jupiter is increasing, and thereby rendering it easier to raise higher tides, and at the same time the cohesive forces are grow- ing less, and of these items the first is favorable to the production of a larger planet mass and the second is favorable to an easier rupture. This situation wiU continue as long as the progressing state of fusion and the decreasing power of co- hesion keep pace with the lessening of the sun's graA-ity by the increase in Jupiter's distance from the sun. But gra-^-ity decreases according to the square of the distance, and fusion does not increase in any such ratio, nor does cohesion decrease in any such ratio, so it is only a question of time when the decrease of gra^-itj- will far outstrip the in- crease in fusion and the decrea,se in cohesion. When this point is reached, gra\'itj' will be imable to pull away such a mass, and there will be a de- cided drop in the size of the planets bom of the direct tide-producing force. Our earth evidently occupies the critical position, and ^lars had to be much smaller, and the original planet from which the asteroids were likely formed must have been somewhat smaller still. ORIGIN OF OUR PLANETARY SYSTEM. 43 If the pulling force could have remained more nearly the same, there would be the same regu- larity in the sizes of the interior planets that we find in the outer ones. During this period of planet forming the indi- vidual gravity of Jupiter, by virtue of which it resisted any effort to disrupt its mass, was not very greatly changed, or at least it did not change as rapidly as some other forces because of the great bulk of Jupiter in comparison with the mass of the various planets of which it was robbed. Now let's turn to the planets on the outside of Jupiter's orbit. Here there seems to be no such varying curve of volume as we find on the inner side. Of the known planets on this outer side there seems to be an almost regular decrease in volume as we move away from Jupiter. In considering this particular turn of the mat- ter it will be necessary to repeat some arguments already made in reference to other matters. But, as we know, the same causes often show their ef- fects in several ways at the same time ; in fact, they are often distributed. When the first inner planet had been pulled 44 ORIGIN OF OUR PLANETARY SYSTEM. away there followed an immense disturbance, as before noted. And as a matter of course the tem- perature was raised, the state of fusion increased or advanced, and the forces of cohesion diminished, all of which tended toward the formation of a larger planet at the very next break. And such a planet of increased size undoubtedly was formed. But the forces in the case of the exterior planets were somewhat different from the forces producing the inner planets. In the case of the inner planets the pull of the sun was directly on the mass that was about to break off and form the inner planet ; in the case of the outer planet the pull of the sun was directly upon the mass of Jupiter which was being pulled away from the mass, or tidal wave, which was about to break off and form an outside planet ; and in addition to this tidal wave having the advantage of being the least affected because of its greater distance from the sun, there were the great oscillating forces which had originated on the inner side of Jupiter and were now pushing in an exactly opposite direction from the way the sun was pulling the body of Jupiter. The result of this was to push off a much larger body of ma- ORIGIN OF OUR PLANETARY SYSTEM. 45 terial than had just been pulled off from the other side of Jupiter. So much for the first outside planet. Now when we come to the pushing off of the second outside planet, we have the assistance of the advanced state of fusion and the consequent lessening of cohesion just as we had in the case of the second inside planet. And this resulted in forming a still larger planet ; and as the tempera- ture increases and the cohesion decreases there will be every tendency for each successive outside planet to be larger than its predecessor on the same side. But you say that we had just that condition on the other side, but the inner planets did not continue to rise in volume throughout the series. No, they did not. They did not, because the grav- ity pull of the sun became too weak. In the case of the outer planet, the gravity of the sun was pulling less and less on the body of Jupiter, but there was this great additional oscillation, origi- nating at the birth of the outer planet's interior mate, that was pushing in the opposite direction from the pull of the sun and thereby counteracting any loss in sun pull that Jupiter would experience by increasing its distance from the sun. There 46 ORIGIN OF OUR PLANETARY SYSTEM. was only the primary oscillation in the case of an interior planet, but there was in the case of every outer planet a great secondary oscillation to help make the break. "UTiile the oscillations must have continued more or less all through the planet- formiag period, there can be no doubt that the time between the birth of each of any pair of planet twins must have been much shorter than the time between the birth of any two sets of twins. There would be some chance for the disturbances to quiet down in some degree between the births of two separate sets of twins. There doubtless would be an increased temperature effect at the birth of the next set, that is, an increase over what it was at the beginning of the birth of the previous set. The temperature curve would rise and fall, but always, throughout the planet-forming age, any low point in the curve would be a little higher than a corresponding point in the previous period, and a little lower than the corresponding point in a subsequent period, registering a little gain in fusion for each birth-epoch over its predecessor. Another point might be of interest here. In the consideration of the inner planets we considered ORIGIN OF OUR PLANETARY SYSTEM. 47 the ratio between the decrease of the sun's pull on account of increase in distance and the increase in fusion with the consequent lessening of co- hesion, and we concluded that the decrease of sun puU outstripped the other elements, and that this caused a decrease in the size of the planet. Now, the puU in the case of the inner planet was on the tidal wave direct, and the mass of the tidal wave in that case was so insignificant in com- parison with other masses in the case that any increase in the distance over which the puU had to act would make a decided decrease in its ef- fectiveness. It would not take a very great in- crease in distance to offset nearly the entire ele- ment for which the mass of the tidal wave was itself responsible, and at the critical point there would be a significant slump in planet size. But in the case of an outer planet the direct pull was not on the tidal wave, but on the entire body of Jupiter, puUing it away from the tidal wave. Now the mass of Jupiter was so great that it could hold up for quite a while in the face of any decrease in sun pull due to distance increased. That is to say, although the sun pull was decreasing as Jupiter 48 ORIGIN OF OUR PLANETARY SYSTEM. moved away, the latter 's mass was so great that, whatever the decrease, there was yet remaining a great residue of pull due to the mass alone, and this cooperated with the forces which tended to form a great planet. So there were extra causes in the production of the volume curve of the outer planets, which do not appear in producing the volume curve of the inner planets. All these influences were working toward a larger planet each time an outside planet was born, and they were working on the broad, deep tidal wave, pushing it from the bottom and not puUing at its top, so that when the rupture came it took away much material from the greater depths of the parent body, where were stored the materials of lighter specific gravity, and this fact gave still further encouragement to the formation of a large planet. Such a combination of forces, with very little counteracting force, broke off the outer plan- ets in increasing size until planet-making culmi- nated in the monster Saturn, the latest and lightest of Jupiter's offspring. In regard to the lighter materials of Jupiter be- ing below the surface and the heavier on the sur- ORIGIN OF OUR PLANETARY SYSTEM. 49 face, the reader will find an explanation in the discussion of requirement (6), which follows. Conies now the consideration of requirement (6) . I am free to confess that this particular require- ment has caused me more perplexity than any- other requirement in the list. The fact that all of the interior planets are of much greater specific gravity than the planets on the outside of Jupiter's orbit is strange, to say the least. How it ever came about that such an arrangement was ever consummated has never been explained except by reasons that are purely fanciful. To state the fact is not enough ; there must be some sort of an explanation somewhere — an explanation that will show the general drift of causes even if it does not lay bare every detail in the case. Requirement (6) has a second phase, namely, that the specific gravity of the interior planets shows a strong tendency to increase as we go from Jupiter toward the sun ; and in like manner the specific gravity of the outer planets shows the same tendency to increase as we go from Jupiter outward toward the known limits of our planetary system. The fact that this grading of the specific 50 ORIGIN OF OUR PLANETABT SYSTEM. gravities is not altogether without some irregu- larities does not discount the tendency in the least, nor does it relieve the investigator from the obli- gation to search for some general law to cover the case. These two phases are very closely related, and as we work out the explanation of one there will appear as a coroUary the explanation of the other. So keep in mind both phases of this particular problem as the solution is presented. I have assumed all along that Jupiter was in more or less of a molten condition. Under no other assumption coidd it be possible for tidal ruptures to take place. So if there was at that time a molten condition sufficient to aUow tidal ruptures, there must have been, at least in the superficial layers of Jupiter, a certain amount of mobility, fluidity, which would be subject to in- crease or decrease according to temperature and pressure. Very well. Now if Jupiter were com- pletely at rest, with neither orbital or axial mo- tion, the molten material would adjust itself with reference to specific gravity as nearly as depth and pressure would allow. The heavier matter OHIGIN OF OUR PLANETASY SYSTEM. 51 would be somewhere below the surface, while the lighter materials would float on the surface. This would be the case for quite a distance below the surface, or until the weight of the superincumbent matter was sufficient to stop any interchange of matter. In such circumstances, if we could bring about a ruptxire the first planet would be composed of the Hghtest material available, that which floated on the surface. And as the lighter mate- rials were used up the heavier materials would be brought into use for later planets, with the result that the interior planets would show a planet of low specific gravity nearest the sun, and a decided tendency for every other planet to be of greater specific gravity as we neared Jupiter, very different from the present arrangement. Also on the outside of Jupiter's orbit there would be a reversing of the present arrangement, showing the hghtest planet farthest from the sun, and with the specific gravity gradually rising until Saturn, the nearest to Ju- piter, would be the planet of greatest specific grav- ity, whereas now it is the planet of lowest specific gravity. But Jupiter is not at rest. It is revolving on 52 ORIGD." OF OUE PLAXETAKT SYSTEM. its axis at a very high rate of speed. It makes a complete revolution in about ten hours. Xow consider that its equatorial diameter is about 88,- 000 mUes, which requires that its equatorial cir- cumference shall be more than 270,000 miles, and you will realize that a point on the equator must travel at the rate of 27,000 mUes per hour in order to make the complete circuit in ten hours. This in round numbers is twenty-seven times as fast as a point on the earth's equator travels. This disparity of equatorial speed would not call for any particular comment in this connection if the force of graA-ity on Jupiter's surface iacreased proportionateh' ; but it does not. WMle the equa- torial speed on Jupiter is twenty-seven times that of the earth, the force of gra^itj' on Jupiter's sur- face is orAy two and one-half times the force of gravity on the earth. Here is a chance for some- thing to happen ; let us see what it is. The mobile materials composing Jupiter's sur- face and the subsurface for some considerable depth will respond to this tremendous centrifugal force, with the result that the heavier materials win gradually work their way to the surface, while ORIGIN OF OUR PLANETARY SYSTEM. 53 the lighter materials will seek the lower depths — just the reverse of what would occur on a molten body that is devoid of axial revolution. This is not new. It is the same old problem of separating the cream from the milk. If the milk is allowed to stand in the vessel the cream will come to the top, and the milk, which is heavier, will settle toward the bottom. But place the unsepa- rated milk in a bowl of the mechanical separator, turn the crank and give the bowl a revolution of high velocity on its axis and the heavier milk will come toward the walls of the bowl, while the hghter cream will collect about the axis of the bowl, whence it may be drawn off without being mingled with the milk. This is exactly the principle that operates on Jupiter ; but Jupiter's materials being less mobile than milk, and the distances much greater, the transferring of the heavier material to the surface would require long periods of time. But once let the heavier materials accmnulate on the surface and they would tend still further to accumulate at the highest point on Jupiter's surface. This point would be the crest of the tidal wave pointing toward the sun. And 54 ORIGIN OF OUK PLANETABY SYSTEM. when the tidal ruptiire came, it would be from this tidal wave crest that would spring the first in- terior planet, and its specific gravity would be de- cided by the excess heavy materials gathered around the sharp end of the ovoid, the point furthest from the center, under the compelling influence of tremendous centrifugal force. Immediately upon the birth of this first interior planet, there occurred, by reason of the reaction from the separation, what was probably the great- est general disturbance that the surface of Jupiter had ever experienced. The result of this disturb- ance was to scatter the superficial heavy material and mix it more or less with the fighter matter, thus, in a great measiire, undoing the work of separation that had been going on, and returning to an average specific gravity. Eight upon the heels of this came the second tidal rupture, the rupture on the side of Jupiter which was turned away from the sun, the rupture which produced the first exterior planet. This, you recall, was the rupture from the great rounded tidal wave, which, being reinforced by this tremendous reaction, took off a much greater amount of material and dug ORIGIN OF OUE PLANETARY SYSTEM. 55 down deeper into the body of Jupiter where it likely got a larger percentage of the lighter matter, and yet did not have the advantage of the heavier material that had been accumulatiag on the sur- face, but with a preference for the opposite side of Jupiter. Here, then, we have a planet of less spe- cific gravity, a specific gravity approaching more nearly the average of the material upon the surface or near it. In addition to these items, it is reason- able to assume that the great mass of this outside planet would enable it to take away with it a much greater quantity of gas, thus still further reducing its specific gravity, for not only could this larger mass take the gas away with it, but it could retain it much more easily than could a body of much smaller mass. These are some of the reasons why we find such marked differences between the specific gravity of an interior planet and that of an exterior planet. But let us follow the matter a little further. After the birth of the first set of twins there would fol- low a long period before the birth of the second set. After the great disturbances caused by the reaction had quieted down, Jupiter would resume 56 ORIGIN OF OUR PLANETARY SYSTEM. his customary business of separating the heavy- material from the Ught, and again the surface would show an excess of heavy material. And each time a rupture took place the smaller inside planet would have a larger percentage of the heavy material than would the outside larger planet, be- cause even if the supply of heavy material from the depths was decreasing, such as reached the surface would respond to the great centrifugal force and accumulate at the crest of the tidal wave from which the interior planets were broken off. What there was of the heavier matter would go, in the main, to the interior planets. I think this is clear. In this connection it might be well to look a little more closely at this phase of the subject — temperature and centrifugal force. It may help us to understand better the fundamental principles of the whole matter. As before mentioned, Ju- piter's tremendous centrifugal force was bringing to the surface as rapidly as possible its heavier material from its depths. Considering that there was a steady increase in the advance of fusion, we would find two results that in a measure would ORIGIN OF OUR PLANETARY SYSTEM. 57 tend to counteract each other. An increase in fusion would of necessity make it easier for the centrif- ugal force to throw to the surface such available heavy materials as lay below the surface, and yet the increase in temperature would tend to melt and mix this heavier material while on its way to the surface and after it arrived there. In the battle between these two features it is more than probable that the rise in temperature would get the upper hand of the transfer of the heavy mate- rial to the surface, because the heavy material was constantly being exhausted from the layers near the surface, and each subsequent installment had to come from a greater depth, had to make a longer trip. That the temperature did get the upper hand is suggested by the fact that the last planet born, Saturn, took an immense jump in size over the preceding planet, as well as showing an unprecedented drop in specific gravity. Both of these incidents indicate an unusual state of fluidity and fusion. And the great drop in specific gravity that characterizes Mars also indicates that there was at that time a considerable increase in fusion; and this increase in fusion might be 58 ORIGIN OF OUR PLANETARY SYSTEM. sufficient to account for the loss or absence of the usual supply of heavy materials, without taking into accottot that the heavy material within available distance below the surface had been de- creased, as it undoubtedly would be in time. And yet the most sensible view to take is that both of these elements were concerned in the reduction of Mars' specific gravity so far below that of the earth, and in causing Saturn to be such an exception in size, characterized by the lowest specific gravity in the whole system. If Jupiter's increasing periheUon distance had not so lessened the sun's puU, and if the excess of heavy materials had not been exhausted at the time of the earth's birth, or if these heaA-y materials had stni been available. Mars would have exceeded the earth both in size and in specific gravity, and the region now peopled by the unnamed asteroids would present to our view a planet worthy of its magnificent twin brother, Saturn, and far and away the most conspicuous member of the interior group. As the matter stands now, the hundreds of aster- oids occupy the place that nature seems to have intended for a regulation planet. In this theory ORIGIN OF OUR PLANETARY SYSTEM. 59 which I have set forth there is no provision for a planetary spawn such as the asteroids suggest. Yet it is not difficult to explain their origin or justify their condition. If I may be allowed to mention the matter of fusion again, I think the riddle of their existence may be answered. Everything points to a maxi- mum condition of fusion on Jupiter at this time. The great increases in the size of Saturn over the size of its predecessor, Uranus, and its unprec- edented drop in specific gravity, both argue a maximum of fusion. And the specific gravity of Mars as well as its size could easily be interpreted to indicate an increase of temperature. For if the matter on Jupiter was hotter it would reduce the cohesion and might cause the interior wave crest to break off at an earUer stage. And the specific gravity of Mars would decline in the pres- ence of a higher state of fusion regardless of whether or not the earth had exhausted the supply of sub- surface materials of high specific gravity. Every- thing, then, leans toward the idea that a maxi- miim condition of temperature was at hand. This being the case, if a planet was produced between 60 ORIGIN OP OUR PLANETARY SYSTEM. Mars and Jupiter it would be in a state of fluidity- far in advance of that of any other interior planet. And conditions mentioned heretofore would re- quire that it should be smaller than Mars. Now a maximum temperature means also that there was a maximum amount of gas and other explosives confined within the molten interior, and when we couple this idea with the fact that the smaUness of the planet would of necessity lower its own indi- vidual gravity force, its own power to maintain its integrity, we are ready to concede that this ultimate interior planet began its existence in a condition of very unstable equilibrium. Any con- siderable shock would initiate an explosion, and the unspeakable forces Avithin would shatter the planet iato milhons of fragments. I can show you the fragments — some of them. They are in the proper place, and many of their characteristics are in keeping with the idea here suggested. But this leads to the question, How did the blow come about, and why did disaster choose this particular planet rather than other shining marks that basked in the sunlight of that ancient day? To answer the question let us remember that the ORIGIN OF OUR PLANETARY SYSTEM. 61 planet-forming ruptures and explosions filled the heavens with fragments ranging from the size of a grain of dust to that of a great moon. The region through which the earth travels is today hterally full of the small fragments, some of which must have had their origin in the planet-forming processes. In those days they were far more numerous, and there were many of great size, com- paratively. All the members of our system have stood bombardment from these fragments, great and small, until today the interplanetary spaces have been swept clean of the greater fragments and comparatively clean of the smaller ones. On the larger planets the bombardment was absorbed and the marks obliterated; they were not in a state of unstable equilibrium, and survived the storming of their surfaces. Our own moon pre- sents abundant but silent evidence that the mar- gin by which it escaped utter destruction through this same bombardment was small indeed. But the region in which this new planet moved was a dangerous one. It was nearest to Jupiter, and it was there that the greatest number and the largest fragments would accumulate. Jupiter's 62 ORIGIN OF OUR PLANETARY SYSTEM. great mass would insure this condition. And it was only a question of time when the blow would fall. Judging from the solid condition of the asteroids, it is evident that the blow did not faU until there had come about considerable solidifi- cation ; the little planet survived many revolutions before the crisis arrived. Dr. C. A. Young, in discussing the theory that accounts for the asteroids by the explosion of a larger planet, states that the relation of their orbits can not be accounted for by a single explo- sion ; but if we assume several explosions, the re- lationship of their orbits presents no insuperable difficulty. In the situation as I have described it everything was favorable for the first explosion. After the first explosion took place it was a fore- gone conclusion that many other explosions would take place, either from causes similar to that which produced the first or from the almost necessary collision of the planet's own fragments, subject as they were to the disturbing proximity of the giant Jupiter. Let me dismiss this now for one other point that needs a word before I leave this gravity requirement (6). ORIGIN OF OUR PLANETARY SYSTEM. 63 The earth is the heaviest planet in the system. It evidently got the lion's share of the heavy mate- rial that Jupiter had been digging up and suppljdng to the interior planets. And it seems probable that the supply of this material was faihng, for Mars dropped in specific gravity. The point I wanted to make, however, is that Neptune, being the twin of the earth, is lighter than it should have been. Earth for some reason robbed its twin, and the twin shows it by dropping below Uranus in specific gravity, when, according to rule, it ought to have a specific gravity greater than that of Uranus. Such little peculiarities when they fit in with a theory tend to lend plausibihty to the reasoning in the case. Although I have been compelled to go into a great many details in discussing requirement (6), I beheve you will agree that every phase of that requirement has been met and explained. Requirement (7) calls attention to the numerous satellites from Jupiter outward, while between Jupiter and the sun there are very few such bodies. This may not be a matter of great consequence, but it should be explained. It is quite clear that 64 ORIGIN OF OUE PLANETARY SYSTEM. it would be difficult to tear away from a great body- any considerable amount of material such as goes to make up a planet without at the same time bringing away numerous fragments, and unless these fragments were driven by a much greater force than that which impelled the planet there would be a decided tendency to accompany the planet in its wanderings. But the less the mass of the planet, the less the ability of the planet to control these fragments ; consequently a small planet of no great mass would likely lose whatever fragments that started out with it. A planet of great mass like Satiu-n could control and retain almost any number of fragments that started out with it, or it could easily pick up and retain such as crossed its path at a later date. But going a little further back, the conditions attending the birth of a small planet are not nearly so conducive to the creation of fragments or satelhtes as were the conditions attending the birth of the large exterior planets. The smaller planets were broken from the crest of a long, peaked wave, but the outer and larger planets were broken from the crest of a wave that was broad and rounded. Now the ORIGIN OF OUR PLANETARY SYSTEM. 65 cross-section of the long, sharp crest was much less than the cross-section of the other, hence when the rupture came, in the sharp crest there would be less molten matter disturbed, less pent up explo- sives released, and consequently fewer and smaller fragments would be formed. Now just the reverse of this would happen when the rounded crest on the opposite side was broken. The cross-section in this case being many times that in the former case, would, when the separation came, release much more powerful explosives, and these same ex- plosives, being far deeper seated, would create many fragments both great and small to accompany the greater planet. Just here is possibly as good a place as any to speak of the retrograde revolution of satellites. When a planet is broken from the parent body, of course there start with it numerous fragments at a greater or less distance from the new planet. Now those that are near will naturally remain with the planet, and others, having been blown to a greater distance but still within the sphere of control, will eventually swing around toward the new planet, and if they pass in front of the primary 66 ORIGIN OF OtJE PLANETARY SYSTEM. they will be caught and swung around in one di- rection, but if they pass behind the primary they will be caught and swung around the planet in the opposite direction. So it is altogether possible for the direct revolving satelUtes to be born under the same conditions and at the same time as the indirect revolving satelUte, both being attendant upon the same primary. If such a combination of direct and retrograde sateUites is found with the same primary, it is easy to see that the retrograde satelhte is not likely to be very near the primary, but more likely to be the most remote from the primary. Jupiter's sateUites are likely such as were blown from his body at the time the planets were broken off, and they were either retained by his powerful attraction or recaptured at a later date. In cases where the planet's axial rotation is re- versed and the revolution of the sateUites is Uke- wise affected, it is Ukely that the whole system has been turned over. Some have explained the retro- grade cases in this way where the planet's motion is also involved. In general we may expect to find the greatest irregularities in those planets ORIGIN OF OUR PLANETARY SYSTEM. 67 and in those satellites that are farthest removed from their centers of revolution. In requirement (8) I have called attention to the distances of the planets from the sun, and incidentally to Bode's law. It is clear that when the first twin rupture took place Jupiter was pushed out of his orbit and thereafter was com- pelled to form a new one. He headed in toward the sun, and as a consequence he made his aphelion turn much nearer the sun than had been his re- cent custom. The result of this change was to cut off quite a little of his orbit's major axis on that end and move the neighboring focus and the aphehon part of his orbit inward toward the sun. We can see that inasmuch as Jupiter, in accord- ance with the law of double stars, had been trav- eling in an exceedingly elongated orbit, any in- ward turn on Jupiter's part must cut off his old orbit only on the aphelion end, and a far greater amount the first time he had the inward impulse than at any subsequent time, for at each alter- ation in the orbit it became more nearly circular. So giving him the same impulse at about the same place at different times would always bring him 68 ORIGIN OF OUR PLANETARY SYSTEM. to swinging inward, but at each inward swing he would shorten that end of the orbital axis consid- erably less than at the preceding time. Now in the case of the outer planets, this would result in the distance from the farthest planet to the next farthest being much greater than the distance from the second farthest to the third, and so on.* These distances, then, which separate the outside planets from each other depend primarily upon the amount of incurve that the rupture causes Ju- piter to take ; and, roughly speaking, in all except one instance the distances of the planets from the sun just happen to coincide with the series of num- bers hit upon by Bode. The impulse which drives Jupiter inward to- ward the sun, or the main part of that impulse, originates when the explosion of the immense in- * Combine this idea with the idea set forth in foot note on page 31, and we have, I think, a very good explanation of the law controlling the distances be- tween the outside planets. All the planets were born on the perihelion end of Jupiter's orbit. The shortening of the aphelion end of the orbit's axis was directly responsible for the increase in the perihelion distance and consequent successive decrease in orbital speed at perihehon. This makes Jupiter's in- ward drop at apheUon proportional to the distances between the outer plan- ets, and more remotely to the distances between the interior planets. The latter being flung toward the sun were more easily controlled by the sun, and hence their distances seem more directly related to successive increases in Jupiter's perihelion distance. But the inter-relation of all these items is clear. ORIGIN OF OUR PLANETARY SYSTEM. 69 terior forces accompanying the tidal rupture re- act upon Jupiter and force him toward the sun. I have already spoken of this impulse, and I called attention to the fact that the outside planet is also driven outward, but not to such a degree as it would be if the sun's attraction were not opposed to the explosive impulse. In the case of the planets within the orbit of Jupiter, the law governing the distances of the planets from the sun is not quite the same as the law governing the outside planets' distances, but these laws are related. You will see this when you call to mind that the amount by which the major axis is decreased on the aphelion end de- pends directly upon the amount of incurve pro- duced in Jupiter's orbit by the tidal rupture and the attendant forces, and since this incurve brings Jupiter nearer to the sun it increases the orbital speed, and, as a consequence, Jupiter goes to a greater distance beyond the sun in making its perihehon turn ; but the increment which it adds to the perihehon end of the major axis is by no means as great as the amount subtracted from the aphehon end of the major axis. The reason for 70 ORIGIN OF OUR PLANETART SYSTEM. this is that the sxm occupies one focus, and this re- quires that when the orbit is shortened all the mov- ing must be done by the apheUon focus, while the focus occupied by the sim only appears to move because the perihelion is projected further away from the sun. So while primarily the changes at both ends of the axis are due to the same influence, the perihelion changes are more remote from this influence than are the aphelion changes. It is quite evident that Bode's law is no law at aU. The real law that governs these planetary distances is the relationship of the several ellipses that figure in the case; or to get at the fundamental prin- ciples, we may sum the whole matter up by say- ing that the planetary distances are dependent upon the properties of the ellipse.* Before passing to the next requirement it may be weU to touch again upon the force that throws Jupiter out of its orbit at the birth of one of the outside planets. The tremendous forces liberated by the tidal rupture certainly are sufficient to accomphsh the change, for these forces are incon- ceivably great. For the sake of impressing upon * Compare foot notes on page 31 and page 68. ORIGIN OF OUR PLANETARY SYSTEM. 71 the reader at least a part of the full meaning of these forces, I quote from Arrhenius, page 92 of his "Worlds in the Making" : "These compounds (on the interior of suns) have to be regarded as the most powerful blasting agents, by comparison with which dynamite and gun-cotton would ap- pear like toys." And it is a recognized fact that comets coming into our planetary neighborhood, traveling in very eccentric orbits are by the plane- tary attraction drawn from these elongated orbits and forced to travel in very much shortened and much more circular orbits. And this force which changes the orbit of the comet, when compared with the forces acting at the birth of a great planet, is Hke a summer's breeze beside a conti- nental tornado. I wish to impress this very vividly upon the reader, because I shall soon have to refer again to this tremendous force when I come to tell you how comets originate. Comes now requirement (9), and demands that we explain the axial rotation of planets. We have seen that according to this double-star theory each planet was torn from a wave crest. Now a wave crest is the highest portion of a wave, and in these 72 ORIGIN OF OUR PLANETARY SYSTEM. particular cases the wave crests from which the planets were torn were the highest points on the surface of the molten sphere. It follows then that these wave crests were rotating with a greater speed than any other part of the globe, so when the new planet was torn off, its top, or that part which was farthest from the center of the parent globe, was moving faster than any other part, and as a mat- ter of necessity the planet began to revolve on its own axis in the same direction the crest was mov- ing before the separation took place. You can readily see that it made no difference whether the wave crest was on the side toward the sun or on the side away from the sun, for all the wave crests were moving in the same circular direction. It follows from this consideration that all the planets not only did originally revolve on their axes in the same direction, but they had to do it, and a child could foretell the direction of that rotation. This situation would tend to make the axis of the new planet parallel with the axis of the original body from which it had been torn, but any one will be able to see that perfect exactitude in this matter would not or could not be expected be- ORIGIN OF OUK PLANETARY SYSTEM. 73 cause so many little items would be injected into the case, causing a slightly different result in each instance.* Later in the history of the planets there un- doubtedly came other influences that modified the axial rotation and, for that matter, may have made changes in the incHnation of the axes. In some cases the axial rotation has ceased, and in others has been converted from direct to retro- grade. And it seems that when a planet has a retrograde rotation its satellites revolve about it in a retrograde fashion. I do not feel it incumbent on me to explain these modifications of axial rota- tion, but sufl&ce it to say that others have already given reasons that in all probability are correct. One explanation for retrograde rotation states that the planet and its moon system have been turned completely over, thus changing both the rotation for the planet and the revolution for the satellites at the same time. In case of a planet whose rotation has ceased, tidal effects have been * And these injected items may have been great enough and so applied as to turn the planet and its moons entirely over, producing a retrograde axial revo- lution. 74 ORIGIN OF OUR PLANETARY SYSTEM. held responsible. The rotation of satellites comes under the same law that governs planets, both in regard to the original rotation and subsequent modifications. In requirement (10) there is a demand for an explanation of the presence of comets in our sys- tem. I think there is a decided tendency at this time to consider comets as members of our system, and if they are members of our system from birth, how did they originate? Can they be explained so as to harmonize with the rest of this theory? Go back for a moment to the long, peaked wave's crest on one side of Jupiter, and the broad, rounded crest on the other side. The cross-section of the peaked wave where it breaks off to form the in- side small planet is much less than the cross-sec- tion of the broad wave, where it breaks off to form the body of one of the giant outside planets. Now when either the small planet or the large outside planet is pulled away from the body of Jupiter, at the places where the molten mass parts there wiU be Uberated forces of enormous explosive energy, and as the pressure is Ufted this explosive energy will throw out at an inconceivable speed ORIGIN OF OUE PLANETARY SYSTEM. 75 quantities of molten material. This material will come from all sides of the fissure and travel at almost all possible angles with Jupiter's plane of revolution with a speed that requires at least a very elongated ellipse for its accommodation. Now notice that there will issue from the break in the broad, rounded wave crest explosive forces far more powerful than will issue from the fissure of the long, peaked wave crest. This is plain, be- cause the wide, deep tidal wave is able beneath its superior weight to retain greater forces. This means that by far the greater number of explo- sions, and the most terrific ones, will come when the giant outer planets are torn away. So the greater number of comets will take their origin from the birth of the outside planets. It wiU be well to remember this. Now another point — an important one. This comet material is expelled by explosions. It is as if a heavenly body exploded, in so far as these comet fragments are concerned, for these explo- sion-born fragments are not due to tidal rupture, but to explosive forces simply released by the rupture. Now it is a law when a heavenly body 76 ORIGIN OF OUR PLANETARY SYSTEM. explodes that all the pieces shall come back to the place where the explosion took place unless some- thing interferes with their return. So these com- ets, blown in almost all conceivable directions, will go out in their remarkably eccentric orbits and, barring outside influences, will come back to the neighborhood where they were born. It is here at this point of return that they make their perihelia. Make a careful note of this point. It is perfectly natural that they should be blown in many directions, and it is equally natural that some of these fragments should be blown in the same direction that the parent body was moving at the time of the rupture, not only in one in- stance, but in every instance marked by a tidal rupture. So they will sweep on in the same gen- eral direction as the parent body and make every effort to have their apheUa coincide as nearly as possible with points in the orbits that they as in- tegral parts of the parent body would have trav- eled had they not been blown from the parent body and the parent body had not been disturbed. This all means that at each particular rupture there will be comets so directed that they will ORIGIN OF OUR PLANETARY SYSTEM. 77 make their aphelia somewhere in the neighborhood of the orbit of their own particular great outer planet, and this particular planet will be the great outer planet born at the same time as this partic- ular group of comets.* Now we can understand why each orbit of the outer planets has a family of comets generically attached to it. And we can also understand the wild confusion characterizing the arrangement of comet orbits and the apparent disregard that comets have for regularity in the angle which their orbits make with the plane of the ecUptic. It is well known that there are no famiUes of comets attached to the orbits of the interior plan- ets. The small planet born from the inner side of Jupiter falls quite a distance inward toward the sun and sets up a new orbit there, and this new orbit is not related to the comet producing * Comets were born when the inside planet was born as well as when the outside planet was produced, practically upon the same orbit. But since it is reasonable to suppose that the most powerful explosions took place at the birth of a great outside planet, it is more than likely that comets now making their aphelia near the orbits of the great outside planets were produced by explo- sions incident to the birth of that planet near whose orbit they have located their aphelia. Explosions incident to the birth of the interior planets were likely less powerful and did not in probability drive comets so far out. How- ever, there must have been at the birth of either interior or exterior planet explosive forces differing very greatly in intensity. 78 OKIGIN OF OUK PLANETAKY SYSTEM. explosions at all. So the planets inside the orbit of Jupiter never had any families of comets at aU; they could not have them. If there ever were any comets associated with the orbits of the in- side planets, or if there are any such now, they are simply pick-ups. The great outside planets are the only ones allowed by law to have comet "families." Strictly speaking, even Jupiter is not legally entitled to a comet family, for just as soon as the comets were bom Jupiter left his old orbit and took up another quite remote from it. But when the comets returned to the neighborhood where they were bom many of them had to cross Jupiter's orbit within the range of his attraction, so he gathered about him a family of adopted children or, if you prefer, he reclaimed a family that he had deUberately deserted in their infancy. Considering the conditions of the case, it is not surprising that Jupiter boasts the largest family of comets. The double-star theory answers so far for the families of comets. But there are groups of comets whose members travel not very far apart and in orbits very much alike. These group comets were ORIGIN OF OTJR PLANETARY SYSTEM. 79 either born together and have since remained closely associated, or they are the results of the breaking up of individuals. We know that indi- viduals do break up, but it is quite reasonable to assume that inasmuch as very many comets were bom at the same time several individuals, in many instances, were hurled away in the same direction and with the same velocity. The single comet presents no diflScult problem for solution. It was simply born and projected in a direction where it found no companions, and its incHnation to the plane of the ecliptic could be anything from zero to ninety degrees. But in passing I might say that comet orbits are remark- ably susceptible to change under the influence of planetary attraction, even going so far as to make it possible to alter the direction of the revo- lution. Now the comet is a child of explosion, and I have spoken of the law that requires the comet to come back to the point where it was born unless violently restrained. If there is anji;hing at all in. my reasoning, we only have to find the neigh- borhood showing the greatest number of comets' 80 ORIGIN OF OUR PLAXETART SYSTEM. perihelia in order to locate the neighborhood in which they were all bom. Astronomers tell us that more than sixty per cent of the known comets have their periheha within forty-five degrees of the line called "The Smi's Way" ; that is to say, these periheha are strung along this line within forty-five degrees from it on either side. Consider- ing the comet's susceptibility to outside influences, this is a remarkable fact. Chambers in his " Story of the Comets," remarks that he does not exactly know who was the first to point out this concentra- tion, but that Denning had reminded him in a pri- vate letter that "the circumstance is so marked that there is certainly some significance in it." (Page 230.) I agree with him, and on the basis of my reasoning I insist that within the region covering fortj'-five degrees longitude on either side of the sun's way aU the comets were bom, and that there is no other reason than this fact to compel the comets to come back to this region and HteraUy crowd it with their perihelia. If comets are bom in this restricted neighbor- hood, it is only fair to conclude that since planets and comets are bom at the same time, then the OKIGIN OF OUR PLANETARY SYSTEM. 81 planets were also born within these same limits. And since these ruptures must have taken place when Jupiter was passing his perihelion, or there- abouts, it must be that Jupiter's perihelion was in that neighborhood at that time, or at those times. We know that Jupiter's perihelion has been at every point within those limits not only once but possibly many times. And it is well to remember that these ruptures could not all have taken place at the same point, for during this planet-forming period Jupiter's increasing orbital speed and various other elements conspired to in- troduce more or less irregularity in the crisis both as to time and locality. And it will not be wise for us to consider that the present comet status of our system is the status that has always existed since the completion of our planetary system. Without a doubt in the past there were many more comets in the heavens than now. It may be that where one sweeps into our vision today, hundreds swept their magnifi- cent trains across a sky that had not yet met the gaze of the human eye. While I am inclined to think that some of the 82 ORIGIN OF OUR PLANETARY SYSTEM. meteoric matter which we encounter from time to time had another and a special origin, yet I am confident that by far the greater part of this me- teoric matter which is scattered throughout inter- planetary space had its origin in the same explo- sions with the comets, although it never assumed the comet form, but traveled in all kinds of orbits, with all kinds of inclinations to the ecliptic until it was claimed by some overmastering command of a greater body. The silent face of our unchang- ing moon bears witness to the immense number of meteoric bodies, even when the moon had become sufficiently solidified to resist destruction by the impacts of the thousands of meteors that stormed its yielding surface. Interplanetary travel was unsafe until the planets had swept up the greater part of this vast army of tramps and incorporated them into their own organizations. Comets are remarkable bodies, but it seems to me the most remarkable features which they dis- play are their constitutional makeup and the physi- cal changes that they undergo while we watch them. I shall not enter upon these matters of constitution and physical changes at this time, ex- ORIGIN OP OUR PLANETARY SYSTEM. 83 cept to say that in my opinion these featiires of the comet are developments of later Ufe, and do not nec- essarily belong in this discussion. Besides, some time ago I published* my theory of the comet's natm-e, and I do not care to incorporate that theory in this paper. But we may conclude that comets are the unavoidable waste in the making of a planet, and, however old they may be, throughout all the centuries of the past they have been dwin- dling away, and if our descendants are on earth at that distant day there will come a time when no more strange messengers from the depths of space will sweep across their sky, and what they know of comets they will cull from their hbraries. Requirement (11) refers to the relative ages of the planets. It is easy to see that the planets were bom in pairs, one on the inside and one on the outside, one a small one and the other a large one. Jupiter's aphelion distance was decreasing and his periheUon distance was increasing, while his entire orbit was becoming more and more circu- lar. The first interior planet was dropped at a time when Jupiter's perihelion was very near the * " The Secret of the Universe." 84 ORIGIN OF OXm PliANETABY SYSTEM. sun and when his orbit reached the limit of its elongation, and he dropped the outermost planet at the same time, but from his opposite side. So the first small planet and the first, or outermost, big planet are of the same age. Then when Ju- piter's periheUon distance had become greater he dropped another pair, so the second small planet from the sun is the same age as the second large planet coming in toward the sun from the outer limits of our system. Saturn and the asteroids are the youngest set of planetary children ; Mars and Uranus are the nejrt youngest in our system ; then come Earth and Neptune. This arrangement leaves Venus and Mercury unpaired. But I be- heve the reasoning in this paper is so complete and so self-sustaining and interlocking that I am justi- fied in stating that there are two more planets yet to be discovered. And these two wiU supply the missing mates for Mercury and Venus. If there is any dependence to be placed in pure reason, I insist that these planets are there, and sooner or later the photographic eye of the telescope will disclose them, thereby stamping the double-star theory as Q. E. D. OEIGIN OF OUB PLANETARY SYSTEM. 85 There is still other evidence of the presence of the two undiscovered planets. There are two comet famiUes that sweep out far beyond Neptune, one about fifty astronomical units from the sun and the other about twice that distance. In ac- cordance with the law of comets which I have set forth these two families of comets go to points near the orbits of two unknown planets ; they go there because it was on these two orbits that they were born. This idea is not altogether new. Flammarion gives the comet of 1862 (iii.), and the August meteors with aphelion distances of about 49 radii of the earth's orbit, and the comet of 1532 and 1661 as members of the family belong- ing to a trans-Neptunian planet. He locates the aphehon of the comet of 1532 at about 48 radii of the earth's orbit, and he places the unknown planet at about 47 or 48 radii. Later Prof. Forbes took up the idea, and soon had a new planet located at about one hundred radii from the sun and with a period of about 1076 years. But Forbes' comet family does not fit in with Flammarion's ; no more does his planet's period fit in with the period of Flammarion's 86 ORIGIN OF OXm PLANETARY SYSTEM. planet, for Flammarion assigns to his planet a period of 300 years. Forbes names eight comets as members of his trans-Neptunian family : 1556, 1840 (iv.), 1855 (i.), 1855 (ii.), 1861 (i.), 1843 (i.), 1880 (i.), and 1882 (ii.). The truth about the matter is that they are both right, for there are two undiscovered planets at just about those distances, and with periods very close to the figures which these two astronomers have given. If these two astronomers considered that they had grounds for locating a new planet apiece when their only ground was the presence of a comet family at the two points respectively, surely I have an a fortiori argument for these planets when I back up their one reason by the fundamental principles that imderlie the very constitution of our whole system. So not only do I assert that the two undiscovered planets are there, but I assert without the suggestion of a doubt that they MUST BE THERE. I think that these last few remarks will effectu- ally dispose of requirement (12) . For every planet within the orbit of Jupiter there must be one on the outside of that orbit, and NO MORE! Unless ORIGIN OF OUR PLANETARY SYSTEM. 87 we can find another planet between Mercury and the sun we must be content to write at the orbit of this second trans-Neptunian planet, "This is the Limit of our Planetary System." And the age-old planet that has traveled this silent path for, it may be, countless millions of his own long years is the ne -plus ultra of the children that under the resistless influence of the sun were torn from the body of the giant Jupiter. A very important corollary claims some atten- tion here. If this double-star theory is correct, there is some ground to believe that once this series of tidal ruptures was inaugurated they could have followed each other at comparatively short intervals of time. I see nothing to hinder the idea that it is possible that the completion of the sys- tem nday have required a much shorter period than we have been accustomed to suppose. And if this theory is true, the binary systems of the universe assume a heretofore unrecognized importance. Doubtless many of them are busy today with planet formation after the manner of our own planetary history. These binary sys- tems are very numerous, and we may conclude 88 ORIGIN OF OUR PLANETARY SYSTEM. from this that world-building comprises no small part of the great purpose of the universe. But worlds, why build worlds if their soil is not to re- spond to the footsteps of conscious life, and if their atmospheres are not intended to vibrate with expressions of joy? This brings me to the close of the argument. I have held rigidly to the exactions of the twelve requirements that are laid down at the beginning of this paper. I fully beheve that this new theory answers every demand of these twelve require- ments ; and in that case I beheve it has the advan- tage of every other theory ever set forth for the purpose of explaining planetary origins. Other things being equal, that theory is best which ex- plains the greatest number of phenomena. I think it will be difficult to find another theory that can explain an equal number of phenomena in this particular field. Again, that theory will be en- titled to precedence which is characterized by the greatest simplicity. I believe this theory com- phes with this requirement, for I have called into action no new laws, I have introduced no new prin- ciples. I have endeavored to explain every detail ORIGIN OF OTJE PLANETARY SYSTEM. 89 of the problem by the application of well known laws and thoroughly established principles, and if I have violated any estabhshed law or principle I am frank to confess that I do not know it. That there may be requirements in this problem other than the twelve that I have specified I do not doubt. I do not profess to know all that is now known about our planetary system, and much less can I predict what new knowledge the future may acquire, but if the credibility of my theory rests upon its conformity to facts already known, its ultimate proof must depend upon the agree- ment between it and the facts that are yet to be bom of the future. The critical point in this whole matter lies in the proper analysis of the planetary system. Given the analysis, and almost any man ought to be able to do the rest. I do not know that I am entitled to any special credit for happening upon this analysis, for I do not know myself how great a part mere chance may have played in the matter. I do know, however, that the matter has been of absorbing interest to me all my Ufe. Never have I tiuned my eyes toward the starry vault 90 ORIGIN OF OUR PLANETARY SYSTEM. without being entranced by the magnificent spec- tacle and thrilled with an intense desire to know the secrets of this stupendous drama of the night. If prayer is the sincere desire of the human heart, then my hfe has been one long prayer, to which the unfolding of this theory may be the answer. I hope it is. For, indeed, no man with a spark of ambition in his soul could contemplate unmoved the coupling of his name for all time with the true solution of this great problem which has been masked in deepest mystery from creation's first morning until now. Cornell University Library 11666 origin of our planetary system, 3 1924 031 323 938 olin,anx