This strange planet of the most ancient God of the Heavens is now visible during the spring and summer months as a faint, greenish star of the 6th magnitude, but it is rather difficult to locate unless the observer is an experienced astronomer. THE BOUNDARY PLANET OF NEPTUNE, THE GOD OF THE SEA _Diameter--35,000 miles_ After the discovery of Uranus in 1781, its pathway among the stars of the sky was carefully noted and geometers were not long in fitting it with an orbit. In a few years, however, it was noted that the planet was out of its computed orbit by a distance as great as the moon's distance from the earth. The deviations attracted general attention and popular opinion feared that the new planet, being so far from the center of the solar system, was breaking away from the sun's control. But a young mathematician, J. C. Adams, and a few months later an older and experienced mathematical astronomer, Leverrier, conceived a more logical solution of the mystery, and decided that they would search beyond Uranus and see if there was not a planet which was attracting Uranus and causing irregularities in the great world's motion. This was a tremendous task, for not only was it necessary to calculate the orbit of the hypothetical planet, but also the weight and speed that such a planet would have in order to pull Uranus in exactly the way that it was being perturbed. After much hard work the problem was satisfactorily solved by each man independently. Challis at Oxford, following the computations of Adams, first commenced to search in the place where these indicated that the planet might be found, and on August 4th, 1846, actually saw and mapped the star but did not recognize its planetary character. On the 23rd of September, 1846, Galle of Berlin, searching at the place indicated by Leverrier, found the new world at almost the exact place indicated by the computations! This should satisfy the most skeptical as to the validity of the great Newtonian law of gravitation and the accuracy of the mathematical deductions therefrom. To prove the existence of a planet and to determine its position before it was ever seen, is considered by scientists to be among the most amazing intellectual achievements ever recorded in history. Neptune requires 165 years to complete a revolution around the sun. The boundary line of the solar system, which is the planet's orbit, is a tremendously long pathway on which to travel, for it lies at a distance of 2,775,000,000 miles from the sun. The length of a day on Neptune is not known as it lies too far away to permit an observer to distinguish any permanent surface features even with the largest telescopes. It has been estimated that as Neptune is so far away from the sun, it receives only ¹⁄₉₀₀th as much light and heat as our earth.