Outside these red flames or “prominences” is the corona, commonly divided into the inner and outer coronas. Many different explanations have been offered of this beautiful crown of light round the sun, plainly visible to the naked eye during an eclipse. But here again we know little, and must be content to watch and wait. CHAPTER III. WHAT BINDS THE FAMILY TOGETHER? What is it which binds together all the members of the Solar System? Ah, what? Why should not the sun at any moment rush away in one direction, the earth in a second, the planets in half a dozen others? What is there to hinder such a catastrophe? Nothing--except that they are all held together by a certain close family tie; or, more correctly, by the powerful influence of the head of the family. This mysterious power which the sun has, and which all the planets have also in their smaller degrees, is called Attraction. Sometimes it is named Gravitation or Gravity. When we speak, as we often do, of the _law_ of attraction or gravitation, we mean simply this--that throughout the universe, in things little and great, is found a certain wonderful _something_, in constant action, which we call a “law.” What the “something” may be, man can not tell; for he knows it only by its effects. But these effects are seen everywhere, on all sides, in the earth and in the universe. It is well named in being called a “law;” for we are compelled to obey it. None but the Divine Lawgiver who made this law can for a single moment suspend its working. What causes an apple to fall to the ground when it drops from the branch? Why should it not, instead, rise upwards? Because, of course, it is heavy, or has weight. But what _is_ weight? Simply this--that the earth draws or drags everything downwards towards herself by the power of attraction. Every substance, great or small, light or heavy, is made up of tiny atoms. Each one of these atoms attracts or draws all the other atoms towards itself; and the closer they are together, the more strongly they pull one another. The atoms in a piece of iron are much closer than the atoms in a piece of wood; therefore the iron is called the “more _dense_” of the two, and its weight or “mass” is greater. The more closely the atoms are pressed together, the greater the number of them in a small space, and the more strong the drawing towards the earth; for the earth draws each one of these atoms equally. That is only another way of saying that a thing is “heavier.” If you drop a stone from the top of a cliff, will it rise upwards or float in the air? No, indeed. The pull of the earth’s attraction, dragging and still dragging downward, makes it rush through the air, with speed quickening each instant, till it strikes the ground. Every single atom in every single body _pulls_ every other atom, whether far or near. The nearer it is, the stronger always the pulling.