Immanuel KantUniversal Natural History and Theory of Heaven |
On the Systematic Arrangement of the Fixed Stars
The theory of the general arrangement of the cosmic structure has not achieved any remarkable progress since the time of Huygens. At this time we know no more than we already knew then, namely, that six planets with ten companions all have their circular orbits arranged almost on a single plane, that they, together with the eternal comets, which run riot in all directions, make a single system, whose mid-point is the sun, towards which everything sinks, around which their movements run, and from which they all are illuminated, warmed, and kept alive, and finally that the fixed stars are just so many suns, the mid-points of similar systems, in which everything may be set up in just as large and orderly a way as in our system and that the infinite space swarms with cosmic systems, whose number and excellence is connected to the infinite nature of their Creator.
The systematic arrangement which occurs in the union of the planets which move around the sun disappeared altogether in the crowd of fixed stars. And it seemed as if the rule-governed relationship encountered in miniature does not hold sway on a large scale among the structures of all the worlds. The fixed stars were subject to no law, by which their paths were confined relative to each other, and we saw all heaven and the heaven of all heavens without order and without design. Since human curiosity limited itself in this way, we did nothing further, other than to derive from this state the immensity of the One who had revealed Himself in such inconceivably huge works and to admire Him.
Wright, an Englishman from Durham, stumbled across a lucky idea, which he himself does not seem to have developed into anything insightful, for he did not make enough observations to produce something useful. He looked at the fixed stars not as a disorganized, scattered swarm without design but saw them in total as a systematic arrangement in a general stellar interrelationship with reference to the principal spatial plane which they occupy.
We wish to develop the idea which he came up with and to try to bring out fully its implications, so that it can generate fertile consequences. The complete confirmation of these will be something left for future ages.
Anyone who gazes at the starry heaven on a clear night will notice the bright band which presents a steady light through the crowd of stars, which are more numerous there than elsewhere and which perceptibly lose themselves in the huge expanse. People have called this band the Milky Way. Because of the structure of this recognizable and distinct area in the sky, it is remarkable that observers of the Heavens were not long ago prompted to derive from it certain conclusions about the locations of the fixed stars. For we see that the band is organized in a huge circle and in a continuous arrangement taking up the entire sky. These two factors are so precisely determined and, in comparison with the uncertainty of chance, with such recognizable indicators, that from them long ago attentive astronomers should naturally have been motivated to trace accurately the explanation for such a phenomenon.
The stars are not placed on the apparently hollow sphere of the heavens, but from our point of view stand at some distance from each other, some further than others, disappearing into the depths of the skies. From this phenomenon it follows that, at those distances where they are located one behind the other in relation to us, they do not occur in an equal scattering in every direction, but must be arranged on some plane which goes through our viewpoint. They are located as close as possible to this plane.
This relationship is such an unambiguous phenomenon that the other stars, which are not included in the white band of the Milky Way, are themselves observed to be that much closer together and more dense, the nearer they are located to the circle of the Milky Way. Thus, of the 2000 stars which the naked eye perceives in the sky, we find the largest number in a relatively narrow area in the middle of which is the Milky Way.
Now, if we imagine a flat plane drawn through the starry heavens and extending an unlimited distance and if we assume that all the fixed stars and all the solar systems have a common spatial relationship to this plane, so that they are closer to it than to any other areas, then the eye which is located on this common plane, as it looks out into this field of stars, into the hollow spherical surface of the firmament, will see the thickest crowd of stars in the direction of the drawn plane, in the form of an area illuminated with more lights. This band of light will sweep out in the shape of huge circle, if the onlooker's viewpoint in on the plane itself. This area will be full of stars. Because of the undifferentiated smallness of bright points, a single one of which escapes the eye, and because of the apparent density of a uniform white gleam, it will look, in a word, like a Milky Way. The rest of the heavenly stars, whose relationship with the drawn plane becomes less and less apparent or which are also located closer to the observer's position, will seem to be more scattered, although their accumulation will be precisely related to this plane. From this finally it will follow that, because from our solar system the system of fixed stars will be seen in the shape of a very large circle, our solar system will be in the same large plane and make one system with the fixed stars.
In order that much better to explore the arrangement of the common interrelationship governing this cosmic structure, we wish to try to discover the cause which has arranged the positions of the fixed stars in this way on a single common plane.
The Sun does not limit the extent of its powers of attraction to the narrow region of the planetary system. According to all observation, this power extends an infinite distance. The comets which go far above Saturn's orbit are forced by the sun's powers of attraction to turn back and move in orbits. Whether it is more likely for the nature of a force apparently incorporated into the essence of matter to act without limits and whether, in addition, it will be really recognized as such by those who assume Newton's principles, we wish only to concede that this power of attraction of the sun extends approximately to the nearest fixed star and that the fixed stars act on each other as just so many suns in the same way. Thus, it follows that the entire host of fixed stars is forced to come closer together through this power of attraction, so that all the world systems are in a situation where sooner or later they fall into one clump, through this reciprocal moving closer together, which is continuous and unhindered, unless these systems are saved from this disaster by forces which pull away from the central point, as with the spheres in our planetary system. These forces prevent the heavenly bodies from falling directly and, working together with the forces of attraction, bring about the timeless orbits. Thus the structure of creation will be preserved from collapse and has been created to last eternally.
Thus, all the suns in the firmament have an orbiting motion, either around one common central point or around many. But with them, we can everywhere apply the analogy of what we observe about the orbital path of our own solar system, namely, that just as that very cause which subjects the planets to a force moving them away from the centre, through which they maintain their orbits, has organized their orbital paths so that they are all on a single plane, so also the cause, whatever it might be, which has given the suns and so many wandering stars of the higher world structure the force of their orbits has also brought their orbits as much as possible into one plane and has worked to limit deviation from this plane.
According to this conception, we can picture the system of fixed stars to a certain extent by means of the planetary system, if we magnify the latter infinitely. For if instead of six planets with their ten satellites we assume many thousands of similar bodies, and instead of the twenty-eight or thirty comets which we have observed, we assume a hundred or a thousand times more of them, and if we think of these bodies as generating their own light, then to the eye of the observer who looks out from earth it would appear as it does with the fixed stars of the Milky Way. For the above-mentioned planets, because of their close relationship to the common plane, would display to us on our earth located in exactly the same plane an area made up of countless stars densely lit, in the shape of a very large circle. This band of light would have a sufficient number of stars everywhere, although, according to this hypothesis, as moving stars, they are not fixed to a single spot. For, because of their movement, there would always be enough stars on anyone side, even though other stars had moved from that location.
The width of this illuminated area, which projects a sort of zodiac, will be set by the different levels of deviation of designated erratic stars from the reference plane and by the inclination of their orbits in relation to this same plane. Since most of them are near this plane, their number will appear more scattered in relation to the extent they are distant from it. However, the comets, which occupy all regions without distinction, will cover the field of heaven on both sides.
The shape of the heaven of fixed stars thus has no cause other than the same systematic arrangement on a grand scale as the cosmic structure of the planetary system on a small scale. All the suns in them make up one system, whose common connecting plane is the Milky Way. Those which are the least related to this plane will be seen to the side of it; for that reason however, they are less dense, more widely scattered, and less frequent. They are, so to speak, comets among the suns.
This new theory, however, attributes a forward motion to the suns, and yet everyone acknowledges that they are motionless and that they have been fixed in their positions from the start. The name which the fixed stars have acquired from this seems confirmed and unambiguous because of all the centuries of observation. This difficulty, if soundly based, would destroy the proposed theory. But this lack of movement, when we consider it, is only apparent. It is either only an exceeding slowness, caused by the enormous distance of their orbits from the common mid-point or an oversight brought about by the distant location of the observer. Let us estimate the plausibility of this notion by calculating the movement of one of the fixed stars located very close to our sun, assuming that our sun is the central point of its orbit. If, following Huygens, we assume that the distance of this star is over 21000 times greater than the distance of the sun from the earth, it then follows from the established law of the time of orbiting bodies, which is proportional to the square root of the cube of the distance from the mid-point, that this star must take more than one and a half million years to go around the sun and, what is more, in 4000 years it would have moved forward only about one degree. Now, perhaps only very few fixed stars are as close to the sun as Huygens assumed for Sirius. Thus, the distance of the rest of the heavenly host perhaps exceeds by far the distance of Sirius, and therefore most of them would take an unusually longer time for such periodic orbits. From this it is also more probable that the motions of the suns in the celestial stars go around a common point whose distance is much further away, and the forward motion of the stars can hence be exceedingly slow. So we can probably assume that all the time which human beings have been keeping records of celestial observations has been insufficient for them to notice the change which has taken place in these stellar positions. We should not, because of this, give up hope that we will discover this change in time. To achieve that will require subtle and careful observations, together with a comparison of widely distant observations. We must direct these measurements especially at the stars of the Milky Way (5), the main plane of all movement. Bradley has observed the almost imperceptible movements of the stars. The ancients marked stars in particular places in the sky, and we see new ones in other places. Who knows that these ones have not just changed position? The excellence of the instruments and the perfecting of our knowledge of the stars give us ground to hope for the discovery of such remarkable and important observations (6). The credibility of the very issue supports this hope on the ground of nature and the analogy so well, that it can stimulate the attentive work of scientists to bring it to completion.
The Milky Way is, so to speak, also the zodiac of new stars, alternately appearing and disappearing in this region in a way hardly matched in any other celestial area. If this alteration in their visibility proceeds from their periodic moving further away and closer to us, it seems clear from the proposed systematic arrangement of the stars, that such a phenomenon must, in all likelihood, be seen only in the region of the Milky Way. For there are stars there moving in very elongated orbits around other stars, as satellites move around their main planets. The analogy with our planetary system, in which only heavenly bodies near the common plane of movement have a companion moving around them, requires that only the stars in the Milky Way have suns orbiting around them.
I am coming to that part of the proposed theory which makes it most particularly attractive because of the sublime picture it presents of creation's plan. The series of ideas which has led me to it is short and simple. It consists of the following. If a system of fixed stars, all spatially related to a common plane, exactly as we have sketched out the Milky Way, is so far distant from us that all perception of individual stars making up the system is no longer possible, even with a telescope, if the distance of this system has exactly the same relationship to the distance of the stars in the Milky Way as the latter has to the distance of the sun from us, in short, if such a world of fixed stars is seen at such an immeasurable distance from the eye of the observer located outside this world, then this world will appear in a small angle as a tiny and weakly lit area, with a circular shape if its plane is oriented directly in the line of sight and elliptical if it is viewed from the side. The weakness of the light, the shape, and the recognizable extent of its diameter will be clearly distinguish such a phenomenon, when present, from all the stars which are seen individually.
We do not need to search a long time for this phenomenon among the observations of the astronomers. It has been clearly confirmed by different observers. People have wondered about its strangeness, have made assumptions, and have subscribed to sometimes wonderful imaginary images and sometimes plausible ideas, which, however, just like the former, had no basis. We are talking about the nebulous stars or, rather, a type of them, which Maupertuis wrote about as follows (7): there are small planets whose light is somewhat more than the darkness of the empty heavens, which all are alike in the fact that they display more or less open ellipses, but their light is much weaker than any other that we are aware of in heaven. The author of the Astrotheology imagines that these are openings in the firmament through which he believed he saw heavenly fire. A philosopher of illuminating insights, the above-mentioned Maupertuis, in thinking about the shape and the recognizable diameter of these stars, considers that they are astonishingly large celestial bodies which display an elliptical shape because of the large flattening caused by their rotation, when viewed from the side.
It is easy to be convinced that this last explanation cannot hold. Because this kind of nebulous stars must undoubtedly be as far away from us as the other fixed stars, not only would their size be astonishing (for in this respect they would have to exceed by a factor of many thousands the largest star), but the strangest point of all would be that with this extraordinary size, made up of self-illuminating bodies and suns, these stars should display the dimmest and weakest light.
Much more natural and comprehensible is the idea that there is no such single huge star but systems of many stars, whose distance makes them appear in such a narrow space, that the light, which cannot be seen for each individual star because of the countless crowd of them, comes out in a uniform pale glow. The analogy with the solar system in which we find ourselves, their shape, which is exactly as it must be according to our theory, the weakness of the light, which this previously mentioned distance requires, all these endorse perfectly the idea that these elliptical figures should be taken as exactly the same world structures and, so to speak, as Milky Ways, whose structure we have just gone through. And if suppositions in which analogy and observations are in full agreement and support each other have the same value as formal proofs, then we must take the certainty of this system as demonstrated.
Now, the attentiveness of the astronomers has sufficient motivation to concern itself with this matter. The fixed stars, as we know, are all connected to a common plane and thus create a coordinated totality, a world of worlds. We see that in the immeasurable distances there are more such star systems and that creation in the entirely of its infinite extent is everywhere systematic and interconnected.
We could further suppose that these higher world orders are not unconnected to each other and through their mutual relationship establish once again an even more immeasurably great system. In fact, we see that the elliptical shapes of these sorts of nebulous stars, which Maupertuis mentions, have a very close relationship to the plane of the Milky Way. Here a wide field stands open for discovery, for which observation must provide the key. The properly named nebulous stars and those about which there is a dispute whether we should call them nebulous must be investigated and tested according to the guidelines of this theory. If we view the parts of nature according to a design and a plan we have discovered, then certain characteristics reveal themselves which otherwise will be overlooked and remain hidden, when observation squanders its time on all objects without any guidance.
The theory which we have proposed opens up for us a view of the infinite field of creation and offers an idea of the work of God appropriate to the infinite nature of the Great Masterbuilder. If the size of a planetary system in which the Earth is hardly seen as a grain of sand fills the understanding with wonder, how delightfully astonished we will be when we examine the infinite crowd of worlds and systems which fill the totality of the Milky Way. How much greater this wonder when we know that all these immeasurable orders of stars once again create a numbered unity, whose end purpose we do not know and which is perhaps, like the previous one, inconceivably large and yet, once again, still a unified system of a new numbered series. We see the first links of a progressive relationship of worlds and systems, and the first part of this unending progression allows us to recognize what we should assume about the totality. Here there is no end, but an abyss of a true infinity, in which all capacity of human thought sinks, even when it is uplifted with the help of mathematics. The wisdom, goodness, and power which has revealed itself is limitless and, to exactly the same extent, fruitful and busy. The plan of its revelation must, therefore, be, just like it, without borders and timeless.
However, there are important discoveries to be made, and not just in large things serving to expand the ideas we can formulate about the magnitude of creation. In small things there is no less undiscovered, and we see even in our solar system the links of a system, which stand immeasurably far from one another and between which we have not yet discovered the intermediate parts. Saturn is the outermost of the wandering stars which we known about. Must there be no more planets between Saturn and the least eccentric comet which perhaps comes down to us from a distance ten or more times removed, a planet whose orbit could approach more closely a comet's orbit than Saturn does? And must not yet other planets be changing into comets by means of a series of intermediate types approximating the composition of comets and linking together the family of planets with the family of comets?
The law according to which the eccentricity of the planetary orbits stands in direct proportion to their distance from the sun supports this assumption (8). The eccentricity in the movement of the planets increases with the distance of the planet from the sun, and the furthest planets therefore come closer to the condition of comets. We can also assume that there are still other planets even beyond Saturn which are even more eccentric and therefore more closely akin to comets, thanks to a continual gradation which finally turns planets into comets. The eccentricity of Venus is 1/125th of the semi-axis of its elliptical orbit; in the case of Earth, the eccentricity is 1/58th; in the case of Jupiter, it is 1/25th, and in the case of Saturn 1/17th. Thus, the eccentricity visibly increases with the distances. It is true that Mercury and Mars are exceptions to this rule, because, according to the law, their eccentricity is much greater than for the extent of their distance from the sun. But we will learn in what follows that the very same cause which made some planets develop a smaller size also deprived them of the impulse required for a circular path, with the result that they were pulled into an eccentric movement. As a result, they were left incomplete in two respects.
Is it not a probable consequence that the increase in the eccentricity of the cosmic bodies located immediately beyond Saturn will be approximately proportional to the ones beneath, and that the planets are related to the family of comets through a less abrupt gap (9)? For it is certain that this very eccentricity is the most important difference between the comets and the planets. The comet's tail and its misty spheres are only consequences of eccentricity. Similarly, the very cause, whatever it may be, which has given the celestial bodies their orbital paths, because of the greater distances not only grows weaker in making the circular momentum equal to the downward force, thereby allowing eccentric movements, but also for this reason is less able to bring the orbits of these spheres into the common plane on which the lower bodies move. Thus is produced the deviation of the comets in all regions.
According to this hypothesis, we would still perhaps hope for the discovery of new planets beyond Saturn, which would be more eccentric than Saturn and also closer to the nature of comets. But for this very reason we would be able to see them only for a short time, when they approach the sun. This factor, the smaller extent of their approach, and the weakness of their light have hindered their discovery and must make that difficult in future. If we wanted, we could call the last planet and the first comet the one whose eccentricity was so large that in its approach to the sun it intersected the orbit of the nearest planet to it, perhaps also with Saturn's.