This idea about Jupiter’s hot and molten state belongs quite to late years. Certain other matters seem to bear it out, though of actual proof we have none. It is thought, for instance, that the dull, coppery red light, showing often in the dark bands, may be a red glow from the heated body within. Also it has been calculated that Jupiter gives out much more light than our earth would do, if increased to his size and moved to his place--more, in fact, than we could reasonably expect him to give out. If so, whence does he obtain the extra brightness? If he does not shine by reflected light alone, he probably shines also in some additional degree by his own light. But what about Jupiter being inhabited? Would it in such a case be quite impossible? “Impossible” is not a word for us to use about matters where we are ignorant. We can only say that it is impossible for us to _imagine_ any kind of living creatures finding a home there, if our present notions about the present state of Jupiter are correct. Then is the chief planet of the Solar System a huge, useless monument of God’s power to create? Not so fast. Even as merely such a monument, he could not be useless. And even if he were put to no present use at all, it might be merely because this is a time of preparation for the future. God has his times of long and slow preparation, alike with worlds, with nations, and with individuals. But now as to the five moons circling round Jupiter. There used to be some very pretty ideas afloat about the wonderful beauty of the moons, as seen from Jupiter, their united brilliancy so far surpassing the shining of our one poor satellite, and making up for the dim light of Jupiter’s sun. A certain little difficulty was not quite enough considered. If anybody were living on the surface of Jupiter, he would have, one is inclined to think, small chance of often seeing the moons through the cloud-laden atmosphere. [Illustration: SATELLITES OF JUPITER COMPARED WITH THE EARTH AND MOON.] The nearest of the four larger moons to Jupiter would, it is true, appear--when visible at all--rather bigger than ours does to us; while the two next would be almost half as large, and the farthest about a quarter as large--supposing inhabitants of Jupiter to have our powers of vision. All taken together they would cover a considerably larger space in the sky than does our moon. But it must be remembered that Jupiter’s moons, like ours, shine merely by reflected sunlight. And so dim is the sunshine at that distance compared with what it is at our distance, that all the five moons together, even if full at the same time, could only give about one-sixteenth part of the light which we obtain from our one full moon.