How many stars are there in the sky? Look overhead some cloudless night, and try to count the brilliant points of light. “Millions,” you would most likely give as your idea of their number. Yet you would be wrong; for you do not really perceive so many. The stars visible to man’s naked eye have been mapped and numbered. It is found that from two to three thousand are, as a rule, the utmost ever seen at once, even on a favorable night, and with particularly good sight. But what is actually the full number of the stars? Two or three thousand overhead. Five or six thousand round the whole world. So much visible to man’s unaided eyes. Ah, but take a telescope, and see through it the opening fields of stars beyond stars. Take a stronger telescope, and note how, as you pierce deeper into space, fresh stars beyond fresh stars shine faintly in the measureless distance. Take the most powerful telescope ever made, and again it will be the same story. There has been a chart or map drawn of known stars in the northern hemisphere--including those visible in telescopes down to a certain magnitude--containing over three hundred thousand. But that is only a part of even what man can see. Sir William Herschel calculated roughly that the number of stars within reach of his powerful telescope, round the whole earth, amounted probably to something like twenty millions. Twenty millions of suns! For that is what it really means. Twenty millions of radiant, burning, heavenly bodies--some the same size as our sun; some larger, perhaps very much larger; some smaller, perhaps very much smaller; but all SUNS. And any number of these suns may have, just like our own, families of planets traveling round them, enjoying their light and their heat. We talk about stars of the first, second, and other magnitudes. Stars can be seen without a telescope as low down as the sixth magnitude; after that they become invisible to the naked eye. This word “magnitude” is rather misleading. “Magnitude” means size, and whatever the real size of the stars may be, they have to our sight no seeming size at all. So when we speak of different _magnitudes_, we really mean different _brightnesses_. The brightest stars are those of the first magnitude, the next brightest those of the second magnitude, and so on. No doubt many a star of the third or fourth magnitude is really much larger than many a star of the first or second magnitude, only being farther away it shines more dimly, or the higher-magnitude star may in itself possess greater natural brilliancy.