Uranus travels through space in an orbit at an average distance of 1,771,000,000 miles from the sun, encompassing the orbits of Saturn, Jupiter, the Planetoids, Mars, Earth, Venus and Mercury; an orbit so large that it takes the planet 84 years to complete its journey around the sun. It has only been a year and a half, according to time figured on Uranus, since Herschel first introduced this planet to earth-dwellers. Although the year of Uranus is 84 of our years long, which causes long and remarkable seasons, its day is very short, for the planet turns so rapidly on its axis that it sees both day and night in 10 hours and 50 minutes. Even the few hours of daylight it enjoys are not very bright ones, or warm ones either, for the planet is so far from the sun (which appears as an intense point of light), that it receives only ¹⁄₃₇₀th as much light and heat as we do on earth. The axis of Uranus is tipped 98 degrees from the perpendicular which causes not only extreme but peculiar seasonal changes. Since the axis of the planet is always pointing in the same direction and at one place in its 84-year journey points almost directly at the sun, each pole in turn is bathed in 42 years of dim daylight and then, when on the other side of the orbit, sleeps through a night that is just as long. Bürgel remarks that "an inhabitant born at the beginning of winter and dying at the age of forty, would never see daylight, or the sun, but live in everlasting darkness like the pit-ponies in coal mines. The contrary would be the case with the summer-born, who would know of night and the stars only from hearsay." Quite different from what life might enjoy on Jupiter, for Jupiter's axis is inclined only 3 degrees from the perpendicular and its year would be almost a perpetual spring. 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.