The alpha centauri paradox: Why the nearest star system is the hardest to see

“ That there is quite room enough within theThe Sun's domain. Sun's paramount domain for their gigantic orbits becomes evident when we consider the distance to which that domain extends. Measured even on the vast scale of our solar system, the gap which sunders it from the nearest fixed star is something enormous. Two hundred and seventy-five thousand times our distance from the sun is the space that divides us from the next sun, the star α Centauri. This distance is found by noting the shift in the star's position due to the extreme swing of the Earth in her orbit called the annual parallax. ”

“ Why I thus compute 1,000 millions of years of light’s radius is because it is possible with powerful telescopes to detect light coming that distance; and when we contemplate that our nearest star, Alpha Centauri, is twenty trillions of miles distant, and 61 Cygni more than twice as [Pg 37] far,—or seven year’s flight of light,—and that the Polar star is some fifty years of light’s flight removed from us; then, if all suns are no nearer to each other than these are to our sun, we are led to believe we may see light with our unaided vision that has been on its journey for a million years. ”

“ Light travels at the rate of about 186,000 miles a second, and therefore leaps the great gulf between our earth and the sun in about eight minutes. But even the nearest of the fixed stars—Alpha Centauri, a star of the first magnitude in the Southern Hemisphere—is so incredibly distant that light takes four years and four months to travel to us from it; while the next nearest, a small star in Ursa Major, is about seven light-years distant, and the star 61 of the constellation Cygnus, the first northern star whose distance was measured, is separated from us by two years more still. ”

“ It requires four and one-quarter years for a beam of light to travel from this star to earth at the rate of 186,000 miles a second, thus showing that Alpha Centauri is about two hundred and seventy-five thousand times as far from us as is the sun, in other words, more than 25,575,000,000,000 miles, which, expressed in our notation, reads twenty-five trillion, five hundred and seventy- five billion miles, a number which the mind of man is incapable of grasping. ”

“ Our astronomical unit and standard of measurement is the distance of the earth from the sun—92,500,000 miles. This is the golden reed with which we measure the celestial city. Thus, by laying down our astronomical unit 226,000 times, we measure to Alpha Centauri, more than twenty millions of millions of miles. Doubtless other suns are as far from Alpha Centauri and each other as that is from ours.
Stars are not near or far according to their brightness. 61 Cygni is a telescopic star, while Sirius, the brightest star in the heavens, is twice as far away from us. ”

“ By convention of astronomers, the average distance between the centers of sun and earth, or 93 million miles, is the accepted unit of measure in the solar system. So the adopted unit of stellar distance is the distance traveled by a wave of light in a year's time: and this unit is technically called the light-year. This unit of distance, or stellar yardstick, as we may call it, is nearly 6 millions of million miles in length. Alpha Centauri, then, is four and one-third light-years distant, and 61 Cygni seven and one-fifth light-years away. ”

“ If a planet equal in size to the “giant planet,” Jupiter, were revolving round the nearest star—Alpha Centauri—at the same distance from that star that Jupiter is from the sun, it would be utterly invisible in our largest telescopes. The invisibility of planets circling round the stars is therefore no proof whatever of their non-existence. Each star of the solar type may possibly be attended by a retinue of planets which may, perhaps, remain forever invisible in the largest telescopes which man can construct. We can, therefore, draw our conclusions only from analogy. ”

“ Further Observations required.—In the case of an object so faint and diminutive as Uranus, a powerful telescope is absolutely required to deal with it effectively. A small instrument will readily show the disk, and present the picture that caught the eye of Herschel more than a century ago, but considerable light and power must be at command if the observer would enter upon a study of the planet’s surface-markings. With my 10-inch reflector I have suspected the existence of the belts, but under high powers the image is too feeble to exhibit delicate forms of this character. ”

“ Still we must not forget that rough appliances do not present an effectual barrier to success. The very finest definition comes only in momentary glimpses. The sharply-cut outlines of planetary configuration cannot steadily be held for long together. Only now and then the image acquires the distinctness of an engraving, when the air and the focus of eye and telescope severally combine to produce a perfect picture. ”

“ "It is of the highest importance in the art of detection to be able to recognize, out of a number of facts, which are incidental and which vital. Otherwise your energy and attention must be dissipated instead of being concentrated. ”

“ Detection is, or ought to be, an exact science, and should be treated in the same cold and unemotional manner. You have attempted to tinge it with romanticism, which produces much the same effect as if you worked a love-story or an elopement into the fifth proposition of Euclid.”
“But the romance was there,” I remonstrated. “I could not tamper with the facts.”
“Some facts should be suppressed, or at least a just sense of proportion should be observed in treating them. ”

“ It is in this manner that you see the material heaven. It is by these invariable laws of optics that you perceive the planets sometimes retrograde and sometimes stationary; there is in fact nothing of the kind. Were you stationed in the sun, we should perceive all the planets and comets moving regularly round it in those elliptical orbits which God assigns. But we are upon the planet of the earth, in a corner of the universe, where it is impossible for us to enjoy the sight of everything. ”

“ And when the last vestige of chaos disappears from the outerskirts of the maturing kosmos there shall appear a glorified universe of indescribable qualities.
Space being a perception a priori cannot be determined wholly by purely objective methods. The yard-stick, the telescope and the light-year are objects which belong exclusively to the phenomenal and with them alone never can we arrive at a true conception of the nature of space. We can no more demonstrate the nature of space by the use of objective instruments and movements than we can measure the spirit in a balance. ”

“ Yet all the knowledge on earth will give me nothing to assure me that this world is mine. You describe it to me and you teach me to classify it. You enumerate its laws and in my thirst for knowledge I admit that they are true. You take apart its mechanism and my hope increases. At the final stage you teach me that this wondrous and multicolored universe can be reduced to the atom and that the atom itself can be reduced to the electron. All this is good and I wait for you to continue. But you tell me of an invisible planetary system in which electrons gravitate around a nucleus. ”

“ We boast our light; but if we look not wisely on the sun itself, it smites us into darkness. Who can discern those planets that are oft combust, and those stars of brightest magnitude that rise and set with the sun, until the opposite motion of their orbs bring them to such a place in the firmament, where they may be seen evening or morning? The light which we have gained was given us, not to be ever staring on, but by it to discover onward things more remote from our knowledge. ”

“ The sun it had left behind it would gradually diminish till it was small as Arcturus, then small as could be discerned by the naked eye, until at last it would finally fade out in utter darkness long before the new sun was reached. Light can traverse the distance around our earth eight times in one second. It comes in eight minutes from the sun, but it takes three and a quarter years to come from Alpha Page 73 Centauri, seven and a quarter years from 61 Cygni, and forty-five years from the Polar Star. ”

“ Were then this star to be suddenly removed from the universe at any moment, we should continue to see it still in its place in the sky for some four years more, after which it would suddenly disappear. The rays which had already started upon their journey towards our earth must indeed continue travelling, and reaching us in their turn until the last one had arrived; after which no more would come.
We have drawn attention to Alpha Centauri as the nearest of the stars. The majority of the others indeed are ever so much farther. ”

“ The sun's attractive power is such that it dominates all surrounding space, even to the fixed stars, so that a body at the distance of our nearest stellar neighbor, α Centauri, which is more than 200,000 times remoter than the sun, could free itself from the solar attraction only by darting away with a velocity of more than 300 feet per second, or over 200 miles an hour ”

“ But, at the same time, if a body moves in the direction of one of the neighboring stars, it begins immediately to receive its influence. The star nearest us is at a distance 210,000 times greater than that which separates the earth from the sun, or eight trillions of leagues; it is the star Alpha Centauri, a brilliant double star whose orbit and mass I have calculated. This mass is equal to the half of that of the sun; it happens that if one could travel from the sun to this star a point would be reached where the attraction of the two would neutralize each other ”

“ AT SIXTY THOUSAND BILLION MILES
Continuing my celestial voyage, I left the system of Alpha Centauri to penetrate into the starry depths of the Southern Cross. I traversed sunny shores and deserts of night, passing from sun to sun, from system to system, flying past stars which blinded me one moment and then were engulfed by the infinite night. The normal state of the universe is night and silence. There is no light except round the suns and planets; there is no sound but in their immediate neighbourhood, in their atmosphere. ”

“ I'm told that the galaxy is a hell of a big place. You've about as much chance of getting there as you have of swimming the Pacific Ocean with one arm tied behind you. Scyth is gone from here so far that it takes light thousands of years to get that far. Hell, Dusty, at this moment, the best resources of all the science of the Earth and the so-called planetary income couldn't move a housebrick from here to Venus in less than a matter of months. Alpha Centauri is actually no more than a dreamer's symbol so far as we're concerned. ”

“ But it is when we turn our observation and our thoughts from our own system, to the systems which lie beyond it in the heavenly spaces, that we approach a more adequate conception of the vastness of creation. All analogy teaches us that the sun which gives light to us is but one of those countless stellar fires which deck the firmament, and that every glittering star in that shining host is the center of a system as vast and as full of subordinate luminaries as our own. Of these suns—centers of planetary systems—thousands are visible to the naked eye, millions are discovered by the telescope. ”

“ So the thought is in us all—a presentiment and a consciousness; and that universal presentiment itself goes far to establish the reality of the unseen order of things to which it is directed. The great planet that moves on the outmost circle of our system was discovered because that next it wavered in its course in a fashion which was inexplicable, unless some unknown mass was attracting it from across millions of miles of darkling space. ”

“ The star we know as the nearest to us in the heavens, Alpha Centauri, is composed of two very bright partners, which take about eighty-seven years to traverse their orbit. They sometimes come as near to each other as Saturn is to the sun. In the case of Sirius astronomers found out that he had a companion by reason of his irregularities of movement before they discovered that companion, which is apparently a very small star, only to be discerned with good telescopes. ”

“ As a rule, when the stars are sparkling and brilliant, the definition is bad; planetary disks are unsteady and the details obliterated in glare. But this is not always so. I have sometimes found in windy weather after storms from the west quarter, when the air has become very transparent, that exceptionally sharp views may be obtained; but unfortunately they are not without drawbacks, for the telescope vibrates violently with every gust of wind and the images cannot be held long enough for anything satisfactory to be seen. ”

“ Venus from her striking brilliancy always leads the novice to expect to see great things on applying the telescope. But aside from a brilliant disk, now a slender crescent, now half full like the moon at quarter, and again gibbous as the moon is between quarter and full, the telescope reveals but little. There is pretty good evidence that the markings thought to have been seen on the planet's surface are illusory, and so it is wholly uncertain in what direction the planet's axis lies ”

“ There are delicate and changing local colors that add much uncertainty. Nevertheless, the planet's leading features are well made out, and their stability since the time of the earliest observers leaves no room to doubt their reality as parts of a permanent planetary crust. ”

“ True character revealed.—As observations began to accumulate it was seen that a parabolic orbit failed to accommodate them. Ultimately the secret was revealed. The only orbit to represent the motion of the new body was found to be an approximately circular one situated far outside the path of Saturn, and the inference became irresistible that the supposed “comet” must in reality be a new primary planet revolving on the outskirts of the solar system. ”