Page:The Music of the Spheres.djvu/296

 Careful observations seem to indicate that Uranus is a gaseous body, although cooler and more solid than Saturn and Jupiter. This planet is immersed in an exceedingly dense atmosphere quite different in constitution from the light, diaphanous covering of air which encloses the ball of the earth. This is indicated by the broad absorption band in its spectrum.

Uranus is attended by four moons but these are too far away for us to observe in any detail. Herschel discovered two of these soon after the planet was discovered, and they were given the names of Titania and Oberon. In 1851, Lassel of Liverpool discovered two more which were called Ariel and Umbriel. Two of these moons are seen with great difficulty even with the aid of the most powerful telescopes. The orbits of these moons are tipped nearly perpendicular to the plane of the orbits of the earth and Uranus, and their movements are retrograde as regards most of the known movements of the solar system.

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.

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