Venus

(Ast.) The brightest and most beautiful of all. the planets, and the 2d in order of distance from the sun. The mean distance of V. from the sun is 66,134,000 miles; her greatest 66,586,000; her least 65,682,000. As the earth's mean distance from the sun is 91,430,000 m., it follows that the distance of V. from the earth varies between abt. 25,000,000 and abt. 158,000,000 m. The eccentricity of her orbit is small, not exceeding 00686. Its inclination to the ecliptic is 3° 23′ 31". Her mean sideral revolution occupies 224-700787 days, and the returns to succe ive conjunctions are separated by a E mean interval of 583-920 days. Her diameter is estimated at about 7,510 m.; her volume 0.855, the earth's being 1; her density almost exactly equal to the earth's; and therefore her ma bears to the earth's the same proportion that her volume bears to the earth's volume. V., like Mercury, but le often, cro es the face of the sun at certain times. This phenomenon,called a transit of V., is of the utmost importance to the astronomer, as affording a means of estimating the distance of the sun from the earth. We owe to Halley the suggestion that the transits of V. might thus be utilized. The estimate of the sun's distance or parallax, was deduced by Encko from the transit of June,1769. Recently,however, doubts were thrown on the accuracy of the observations made in 1769, and it was proved by Prof. S. New com be that the cause of the discrepancy is to be looked for in a phenomenon due to irradiation, which causes ab lack ligament to appear between the disc of V. and the sun's limb near the time of the internal contacts. The U. S., in unison with most European nations, sent astronomers to various remote places to observe the transit which took place on Dec. 8, 1874. Several of these observers were very succe ful in taking photographs of the contacts, but time must pa ere their calculations can be completed and compared with those of the foreign astronomers, so as to come to a more accurate estimate of the sun's distance. The next transit will occur in 1882. [s. 933]