Rensselaer Union, Volume 7, Number 20, Rensselaer, Jasper County, 4 February 1875 — The Sun Hoax. [ARTICLE]

The Sun Hoax.

The Ttibune of the 18th Inst, contained a dispatch from New York' which stated that a solar, parallax of 9.24 seconds or arc was the average result of four independent computations made by as many different Eoglish calculators from the observation* made of the transit of Venus on the Bth of last December. The dispatch also contained a statement pur potting to be made by a gentleman “singularly competent to pass a luminous and comprehensive judgment upon the matter it relates to.” That “judgment" was to the effect that the earth is possibly approaching the sun, at a rate wh.ch Will precipitate our globe into the solar orb in not more than 1,440 years irom this date. On the following day the Tribune stated editorially that we are not nearing the sun, as “ astronomers know and can prove that what is known as the mean distance is almost exactly the same as it was at the date of the transit of Venus in 1709." The sensational dispatch above retorted (o has, however, excited so much curiosity that a mere denial is scarcely sufficient to allay it, though made by such an eminent* authority as “ the as tronoiner of the Chicago Tribune." We therefore proceed to give, in brief, an idea of the process of reasoning on which our statement was based. It is fortunate for this purpose that the sensational communication which was published in full rin the New Vor.k JlYxhlofltke 18tn inst. contained the assurance that, whatever happens, “Kepler’s and Newton’s laws will govern the universe all the same.” Therefore, if we can prove by reference to those laws that the earth is not falling toward the sun, even the “ singularly compel ent" Eastern astronomer must concede that there is no scientific basis for the supposition that the earth is any nearer to the sun than she was in the last century. One of the three laws of Kepler is that the square of the time of revolution is proporional to the cube of the distance. We now know that the law should read to the effect that the sura of tne attracting masses into tbe square of the time, divided by the cube of the distance, is a constant quantity. In the present case we may neglect the modification and look at the operation of the law as stated by Kepler. If, during tue little more than a century that elapsed between the transits of 17(39 and 1874, the distance of the earth from the sun has decreased from 95,250,000 miles to 88,460,000 miles, the, year has also been decreased from 365jdays to 327 days of twenty-four solar hours each. We know that this is not the case, Ike earth now occupies just as much time in one sidereal revolution around the sun as she did a century ago. Hence she is no nearer to the sun now tlian she was then. The objection may be raised that, if the length of the day has been correspondingly shortened, we have no means of detecting a change in the length of the year. But we know that the velocity of the eartn’s rotation on her axis is the same now as then to wiriiin an almost infinitesimal fraction. The length of the pendulum that vibrates 86,-UK) limes lii one solar day is not changed; and we may add that the shortening of the distance of the earth from the sun would really tend to lengthen the day, if, as is suspected, there be a resisting medium in space, the density of which increases as the distance from the sun decreases.

The chance that the rotation of the earth ou her axis w r ould be by any cause accelerated in the same ratio as iter revolution is only as one to several thousand millions. But, supposing this difficulty to be obviated, we have another mode of comparison which could not possibly be affected in that way. A century ago the moon completed twelve lunations in about eleven days less than a year, and she travels around the earth at the same rate now. The laws of motion enunciated by Kepler, and demonstrated by Newton, show that the motion of the earth and moon around each other is affected by the sun. Toe perturbing influence oi the central body of our system causes the moon to occupy about one hour more in passing from one new moon to the next than she would occupy if the mutual atti action of the earth and moon were undisturbed by the sun. And this disturbing effect varies inversely as the cube of the sun’s distance. If, therefore, the distance of the sun had diminished, as stated, the retardation would have been increased to one hour and three-quarters; and each lunation would be about three-quarters of an hour longer than it was a century ago. The moon and earth would thus swing around each other only eleven times (synodieally) instead of more than twelve times, while both journeyed once around the sun, if they were 7,000,000 miles nearer to him than in 1769. But anyone who will take the trouble to look in the almanac will find that between Jan. 7 and Dec. 27 of the present year we have twelve complete lunations set down, and he need have no fear that "they will not all be performed in the time specified, as they were last year, or that the shortest day in 1875 will occur in less than 365 days after the shortest day of 1874. The fact that the ratio- of the length of the lunation to the length of the year continues very nearly the same through the lapse of many centuries proves to us that the relative distances of the sun and moon continue very nearly the same. The fact that the ratio of times does vary by a very small quantity is partially due to the slow change in the lapse of the earth’s orbit referred to in our article of the 19th inst. But Laplace long since pointed out the cause of that change, and proved it to be a periodic one. which will never be the means of bringing us into collision with the sun. The mean distance of the earth from the sun is the same now as it was in the last century, whether that distance be 88,400.000 or 95,250,000. oreany other as-.-ignable number of miles. —Chicago Tribune. Jan. 24.