Fig. 533.—Jupiter.
Fig. 534.—Saturn.
Satellites, however, or “planetary moons,” as they are sometimes designated, are plainly perceived attending upon the great planets. There are twenty of these at present under observation. One we are all familiar with, and the moon, par excellence, lends a beauty to our nights which no other light that we can enjoy or command can ever do. It is remarkable that only this moon is specially mentioned in the Bible in connection with the sun. The stars are usually grouped, although, of course, the sun and moon are equally “stars” in the firmament. Mars possesses two moons and Jupiter four; Uranus also rejoices in the latter number; Neptune, like the Earth, has only one. It is reserved for Saturn to outstrip all the rest in his attendants, for no less than eight satellites wait upon that enormous planet. No doubt there are many more of these moons to be found, and every year will doubtless bring us further knowledge respecting them. Mars’ moons were only discovered very lately (in 1877), although they were known to exist; but being very small, unlike the others, they were missed. So we may conclude that the remaining satellites will remain for some time undiscovered, even if they actually are in existence. Jupiter’s moons are supposed to be as large as our own moon; Neptune and Uranus can boast of equally-sized attendants. But it is impossible to estimate the riches of astronomical lore which are beyond our ken. Millions of tiny planets are believed to exist, but their immense distance from us precludes all investigation. We are but mites in the scale.
Fig. 535.—Meteor shower.
Meteors, to which we have already referred, are small erratic bodies rushing through the planetary system, and getting hot in the process, appear in the atmosphere surrounding our earth as “shooting stars.” Some of these falling bodies have reached the earth, and several can be seen in the British Museum. Numbers, of course, are burnt up before they reach us, and who can tell what destruction such a catastrophe may represent, or whether it be or be not an inhabited world which has thus plunged to destruction by fire? They are of a metallic or stony nature. On certain nights in August and November it has been calculated that these meteors will appear. They fall from certain constellations apparently on these occasions, and are called after their names—as Leonides, from Leo, in the November displays.
Fig. 536.—Star shower.
The star-showers at times attain the dimensions of a very beautiful display of rockets. Millions of them rush round the sun; and when, as occasionally happens, our earth comes near them, we have (as in 1866) a grand display of celestial “fireworks.” But the individuals composing the mass of falling stars are very small. These meteors are very much like the comets we last year had an example of, and it has been lately suggested that there is a great degree of affinity between the comets and the meteors;—in fact, that a comet is merely an aggregation of meteors. They have been supposed to be bodies of burning gas. Their mass is very great, and their brilliant tails are many millions of miles in extent.