With the discovery of Uranus astronomers began to hope that yet other bodies belonged to our solar system. They saw that the motion of Uranus was often disturbed, as if some other planet near it exercised over it some attracting force. Searching carefully, a planet was finally found, about one hundred times larger than the earth, and so far from the sun that to an observer placed upon it the sun must appear like a large star; even the planet’s day would be no brighter than twilight. This new-found planet was named Neptune, and is thus far the last known planet of our sun system. Its place was determined in 1846. Neptune is the only great planet that has been discovered by a set search in the heavens for it, based on reasoning that such a planet ought to exist. A Frenchman and an Englishman discovered Neptune almost simultaneously. The planet has one moon. Uranus and Neptune are so exceedingly distant from our earth, and from the sun, that the study of them has afforded very little of interest. FOOTNOTES: [17] Professor Newcomb considers Jupiter partly self-luminous. [18] Sir B. Ball says 36 millions; others 35 millions; Newcomb makes mean distance 40 millions. [19] Sir R. S. Ball. Story of the Heavens, p. 161. [20] These phases can be observed only through a telescope. LESSON IX. THE KING OF THE DAY. “In them hath he set a Tabernacle for the sun, Which is as a bridegroom coming out of his chamber, And rejoiceth as a strong man to run a race, There is nothing hid from the heat thereof.” --_Psalm XIX._ If it should happen that the sun were blotted out, our earth would at once cease to be habitable. Within forty-eight hours the globe would be covered with a deluge of rain, and buried in piles of snow, owing to the condensation of all the moisture in our suddenly chilled atmosphere, while more than Arctic cold would freeze the oceans to their depths. In this reign of cold and darkness all animal and vegetable life would perish. All the planets of our system would share the same fate, and as the light with which they shine is reflected from the sun, they would become invisible, rolling on through space in total darkness. How far from us is this sun, so important to us as the centre of light, heat, and attraction? Ninety-two millions of miles. But how far is that? An engine running thirty miles an hour, without once slacking speed, could go around our globe in thirty-five days. Start it off for a trip to the moon, and with the same speed it would reach there in eleven months. And then send it from the earth to the sun, at an equal rate of travel: year after year it must rush on, until three hundred and fifty-one years were passed before it could reach the sun. But so much faster does light travel than a railroad train, that light comes to us from the sun in eight minutes and nineteen seconds! [Illustration: “THE LIGHT AND THE NIGHT.”]