The following lively picture is borrowed from the graphic pages of M. Flammarion.
There is more variety, he says, in the innumerable star-systems which crowd the fields of space, than in all the changes which the most skilful opticians can project on the screen of a magic lantern. Some of the planetary universes lighted up by two suns display the entire gamut of colours above blue, but are without the sparkling tints of gold and purple which contribute so greatly to the luminosity of our world.
In this category may be placed certain systems situated in the constellations of Andromedæ, the Serpent, Ophiuchus, and Coma Berenices.
Others are illuminated by red suns, as, for example, a double star in Leo.
Others, again, are wholly dominated by blue and yellow, or, at least, are kindled by a blue sun and a yellow sun, which afford but a limited series of the tints or shades comprised in the combinations of these primitive colours; such are the systems of Ceta, Eridanus (where one is straw-coloured, the other blue), Cameleopardalis, Orion, Rhinoceros, Gemini, Boötes (where the greater one is yellow, and the lesser a greenish blue), and Cygnus (where the smaller is "blue as a sapphire"). On the other hand, combinations of red and green may be found in Cassiopeia, Coma Berenices, and Hercules.
There are other stellar systems which, according to Flammarion, more nearly approximate to our own, in the sense that one of the suns illuminating them has, like ours, a white light,—the source of all colours,—while its neighbouring luminary casts a permanent reflection upon everything. Such, for instance, are the worlds revolving round the great sun of Alpha, in Aries; this great sun is white, but a smaller sun is constantly visible in the sky, whose azure reflections cover as with "a diaphanous veil" the various objects exposed to its rays. Number 26 in Ceta presents the same conditions, which are those, too, of a great number of the most brilliant stars. In the case of the worlds gravitating round the principal world of these binary systems, the originative white lustre would appear to create the infinite varieties noticeable upon the earth, with the distinction, of course, that an azure gleam constantly issues from the other sun; but for the planets gravitating round the latter, the predominant colouring will be blue, tempered by the action of the remoter white sun.
And just as white suns have blue suns for their companions, so have red suns yellow, or vice versâ. What a strange and curious radiance—like that of "a dome of many-coloured glass"—must be shed upon a planet by its red and green or yellow and blue suns! What striking contrasts, what fairylike changes, must be produced by a red day and a green day succeeding alternately to a white day, or a day of darkness! Why do not our poets take up such a theme as this? Can they find aught more remarkable or more eëry in the dreams of their imagination?
Supposing that these wonderful spheres are surrounded, like Jupiter or Saturn, by a ring of satellites, what can be their aspect when lit up by several suns, each sun a source of different-coloured light?
This one, we may imagine, will be divided into hemispheres, red and blue, that will suspend in the firmament a crescent of gold; another will seem to drop from the azure circle like a gorgeous cluster of emerald fruit. Ruby moons, opaline moons, moons of jasper and amethyst,—all shining with a mystic and indescribable radiance,—surely the heavens are decked with jewels like an Eastern queen!