Rensselaer Union, Volume 7, Number 7, Rensselaer, Jasper County, 5 November 1874 — The Secret at Venus. [ARTICLE]

The Secret at Venus.

The planet Venus possesses a secret Of the greatest value to the scientific world. One might conclude as much when he notices, after the setting of the sun, what a commanding position she assumes near the horizon in the southwest, and how significantly intelligent appears her blushing, radiant smile. This wonderful secret she has kept ever since the morning stars together sang their first chorus—ever since God spake into existence the rolling, fiery worlds that people immensity. This is longer than secrets are usually kept by those who worship at the shrine of Venus! It was not till the beginning of the eighteenth century, about 155 years ago, that Venus was suspected of holding so selfishly in her possession this coveted information. Dr. Halley then discovered the important fact, and nroposed that by dome artifice she be induced to divulge the secret. To say nothing of her usual sispositicfii or indisposition to respond when addressed, it is only at special periods that Venus can at all be approached upon this particular subject. Since the discevcry two of the periods have passed—one on the sth of June, 1761, the other on the 3d of June, 1769. To the first questioning a distinct response was refused. To the second Venus replied, but not plainly. And now, almost breathless, —we await the coming of the next period. This will be the 8/A of December, 1874. Then will be repeated the same question, with the greatest possible emphasis. Then, too, on account of this very importunity will we fondly expect her to look down from her celestial abode and distinctly to speak out her response far above the profoundly low and deep-toned music of spheres. Fondly, too, will we expect her utterance to be recognized and echoed and reverberated to every planet and every star throughout the universe. Even now, as she twinkles in the twilight, she seems half inclined to break the stillness of the‘night by revealing her secret before the time.

The secret of Venus is nothing less than the parallactic angle of the sun; that is, the angle contained by two lines drawn drum the center of the sun. one to the center of the earth, the other a tangent t > the earth. Upon the accuracy with which this angle is measured de--pend, directly or indirectly, all astronomical distances—the distances of the earth and all other members of the solar system from the sun, and the distances of the fixed stars from the solar system and the velocity of light. It is difficult then fully to appreciate the real value of this secret when it is once in the possession of the scientific world. The motions of Venus and the earth around the sun are such that at the successive intervals of 121 J years, eight years, 1051 years, eight years, 1211 years, and soon, the planet,in passing between the earth and the sun, is so neat’ to a line joining the centers of the earth and the sun that it will appear to traverse the sun’s face: This is called a transit of Venus. The first transit known to have been observed occurred on the 4th of December, ; the second on the sthof June, 17r>; the third and last one in the past, on ' ie ,3d of June, 1769. The'first one in the future will occur on the Sth of Deceml 1874; the second on the 6th of December, 1882; the third on the 7th of June. 2064. In the interval of 105* years elapsing between the last transit and the next, the earth Trill complete 105| revolutions around the sun, whilst Venus, in the same time, will complete 1711 revolutions around the same central body. It is plain, then, that in this interval Venus will complete precisely sixty-six revolutions more than the earth; that is, at the time of the next transit, she will be passing the sixty-sixth time between the earth and the sun since the last transit. However, sixty-five of these passages were not sufficiently near the line joining the centers of the earth and the sun as to appear upon the sun’s face; and, as the interval between these passages is about 584 days, the sixty-five have already occurred, and nine-tenths of the time has elapsed between the sixty-fifth passage and the next transit of Venus. Venus, our present beautiful eveningstar, therefore, having passed around beyond the sun, and having attained her greatest eastern elongation, is now sweeping alon&toward a point between the and the sun. The time of her setting is coming nearer and nearer that of the sun, and, at the time of the transit, it will be the same. After the transit she will set and rise before the sun, and will again be our morning-star. Since only that half of a planet shines which is toward the sun* the part turned toward the earth at the time of the transit will be thoroughly dark, and it will appear to be a round Black spot on the face of the sun. The diameter of Venus is only about 1.120 of the diameter of the sun; but, as her distance from the sun Is only about three-fourths of the distance of the earth from the sun, the planet will be at a point about one-fourth of the distance from the earth to the sun; and, hence, the diameter of the spot, as compared with the diameter of the sun, will be about four times its real length. The diameter of the spot will, therefore, be about one-thirtieth of the diameter of the sun. This apparent great black bead will pass over the face of the sun from left to right, and the phenomenon will last four hours. On the Bth of December, 1874. the transit will begin about eight o'clock p. m. and will end at about 11:45 o’clock p. m.. Chicago solar time* The phenomenon, therefore, will not be risible in the United States.

To those points of the earth on longitude about 190 degrees east of Greenwich the transit will begin on the 9th at about ten o’clock a. m. and end about two o’clock p. m., and the middle of the phenomenon will occur at noon. This meridian passes through the eastern part of Asia and the western part of Australia. Near this line will be the most favorable positions from which to take" observations on the transit. As the declination of the sun at the time of the transit will be about twenty-two and a half degrees south, to one located on latitude as many degrees south and on the previouslymentioned longitude, the sun, at the middle of the phenomenon, will be precisely in the zenith. At this instant the transit will be visible at all places not exceeding ninety degrees from this point. This point will be found in the western part of Australia; and this dis tance will extend as far to the east on the equator as longitude 150 degrees west, and as far to the west on the equator as longitude thirty degrees east. North of the equator this distance will •Mr. E. Colbert is ODr authority for the rtatement that the transit will begin at 7:58 p. tn. and end at 12:3b a. m., Chicago ume, instead of at 11:45 p.m.. . above stated. This will give 4 hours 38minute* as the duration of the transit. —Ed. Tatauns. - . •* -

not extend so far to the east and west and it will lack twenty-two and a half degrees of reaching to the north pole. South of the equator it will extend somewhat farther to the east and west and it will reach twenty-two and a half degrees beyond the south pole to a point about three-fourths of the distance from the pole to the southern point of South America. The former part of the phenomenon will be visible from points still farther to the cast at sunset; and the latter part from points still farther to the west at sunrise. The next transit of Venus will be a most interesting occurrence. So important, too, is it considered, that our own Government has appropriated a very large amount of qjoney for the complete equipment of several parties of our own scientific men for the work of taking accurate observations from various favorable positions. Other leading Governments have taken hold of the work in a similar manner. Many months ago did the work of preparation begin. A few more will complete the temporary observatories and all their intricate appointments. Then a few hours of rest and stillness, broken only by petitions for absence of clouds, and the scene which has not been witnessed by an inhabitant of earth for 1054 years will burst upon the view of the observers, almost powerlessly intoxicated with excitement. Tne transitof Venus having occurred, the whole Scientific world will, with the intensest anxiety, await the result of the observations — will breathlessly listen for the echo resounding from the utterance of the wonderful secret of Venus. — Carthage College (lII.} Cor. Chicago Tribute: