A few stars are known which are hardly bigger than the earth, but most of them are so large that hundreds of thousands of earths could be packed inside each and leave room to spare; here and there we find an immense star large enough to contain millions of millions of earths. And the total number of stars in the universe is probably something like the total number of grains of sand on all the sea-shores of the world. Such is the littleness of our in space when measured up against the total substance of the universe.
These millions of stars are wandering about in space. A few form groups which journey in company, but most of them travel alone. And they travel through a universe so immense that it is very, very rare event indeed for one star to come anywhere near to another. For the most part each star makes its voyage in complete loneliness, like a ship on an empty ocean. In a scale model in which a million miles from its nearest ship will be well over a million miles from its nearest neighbor. From this it is easy to understand why a star seldom finds another anywhere near it.