"When the keen north wind with all its fury blows, Congeals the floods, and forms the fleecy snows, 'Tis heat intense to what can there be known; Warmer our poles than is its burning zone. Who there inhabit must have other powers, Juices, and veins, and sense, and life, than ours. One moment's cold, like theirs, would pierce the bone, Freeze the heart's blood, and turn us all to stone." --_Baker's Universe._ The sun, as viewed from Neptune, would look very small, not much larger than Venus does to us when she is nearest the earth, although he gives to Neptune 250,000 times more light than Venus gives to us at her best. Neptune possesses only one known satellite. This satellite has the peculiarity of whirling much as if it had been tipped over through an angle of 150 degrees, which causes it to move in a direction opposite to that in which the planets travel around the sun. CHAPTER XVI THE EARTH A PLANET AT CLOSE RANGE _Diameter--7927 miles_ VOLUMES could not cover the extremely complex history of the earth, nor picture with justice the exquisite construction of even its smallest features. It is here that the astronomer puts away his glass and turns detective with the geologist on his own home ground. Astronomers, basing their computations of the earth's age upon the rate at which the sun is shrinking or contracting, have placed it at 25,000,000 years, but geologists claim that this is too short a time to account for the enormous thickness of stratified deposits, the salinity of the ocean, and other similar evidence which seems to prove that it is probably 100,000,000 years old, or even older. Later estimates based upon other modes of production of solar heat may extend this estimate several hundred fold. The moon is believed by some to have once been a part of the earth and that it was formed through a division of the earth's ball when our world was in an early stage of evolution. Becoming two separated bodies, they have remained bound together by mutual attraction, and thus move around the sun. According to the Nebular Hypothesis expounded by La Place, the earth and moon once shone like stars but, through the long ages of time they have gradually cooled, and, their lights extinguished, two cold-surfaced globes now wend their way around the sun. [Figure 155: THE EARTH, SEEN FROM A DISTANCE. (Used by permission of the publishers, Rand McNally & Company, from Dodge's "Elementary Geography.")] The smaller of these two globes is now scarred and old but the other is still fresh with sparkling waters, green verdure, and is teeming with life. According to the later and more generally accepted Planetesimal Theory of Moulton and Chamberlain, these globes were cold in the beginning but became hot through compression as the material of which they were composed was drawn toward their centers by the pull of gravitation.