The third of which the distance has been measured is the small star in Cygnus, already referred to in Chapter II, in describing the Constellations. Its distance is 69 trillion kilometers (42-1/2 trillion miles). This, too, is a double star. The light takes seven years to reach us. As we have seen, the fine stars Sirius, Procyon, Aldebaran, Altaïr, Vega, and Capella are more remote. Our solar system is thus very isolated in the vastness of Infinitude. The latest known planet of our system, Neptune, performs its revolutions in space at 4 milliards, 470 million kilometers (2,771,400,000 miles) from our Sun. Even this is a respectable distance! But beyond this world, an immense gulf, almost a void abyss, extends to the nearest star, [alpha] of the Centaur. Between Neptune and Centauris there is no star to cheer the black and cold solitude of the immense vacuum. One or two unknown planets, some wandering comets, and swarms of meteors, doubtless traverse those unknown spaces, but all invisible to us. Later on we will discuss the methods that have been employed in measuring these distances. Let us now continue our description. * * * * * Now that we have some notion of the distance of the stars we must approach them with the telescope, and compare them one with another. Let us, for example, get close to Sirius: in this star we admire a sun that is several times heavier than our own, and of much greater mass, accompanied by a second sun that revolves round it in fifty years. Its light is exceedingly white, and it notably burns with hydrogen flames, like Vega and Altaïr. Now let us approach Arcturus, Capella, Aldebaran: these are yellow stars with golden rays, like our Sun, and the vapor of iron, of sodium, and of many other metals can be identified in their spectrum. These stars are older than the first, and the ruddy ones, such as Antares, Betelgeuse, [alpha] of Hercules, are still older; several of them are variable, and are on their way to final extinction. The Heavens afford us a perennial store of treasure, wherein the thinker, poet or artist can find inexhaustible subjects of contemplation. You have heard of the celestial jewels, the diamonds, rubies, emeralds, sapphires, topazes, and other precious stones of the sidereal casket. These marvels are met with especially among the double stars. Our Sun, white and solitary, gives no idea of the real aspect of some of its brothers in Infinitude. There are as many different types as there are suns!