EDITED BY MRS FRANCES HODGSON BURNETT. [COPYRIGHT]. The Geography of the Moon. SIR ROBERT BALL, Astronomer-Royal of Irlland. [ALL RIGHTS RESERVED.]

Te Aroha News, Volume VII, Issue 424, 30 November 1889, Page 3

EDITED BY MRS FRANCES HODGSON BURNETT. [COPYRIGHT]. The Geography of the Moon. SIR ROBERT BALL, Astronomer-Royal of Irlland. [ALL RIGHTS RESERVED.]

We are all naturally inclined to take an interest in our neighbours. We like to know who those are that live neir us, and we are not unfrequently curious to learn what we can about them. In a somewhat larger sense, every town is naturally interested in- the affairs of the other towns in the vicinity, and each State keeps a careful watch upon the proceedings of other States which' lie around. It is, therefore, only reasonable that the inhabitants of this particular globe should endeavour to become acquainted with the nature and circumstances of the other globes above us and below us, to our right and to our left. Especially are we to search out all that wo can about that one wOrld which happens to lie comparatively near us. The neighbour to which we refer is the moon. Let ua compare her distance with that of some of the other heavenly bodies. The sun is, for instance, about 400 times as far. Some of the planets do occasionally approach a little closer than the sun, but under all circumstances they remain at least 100 times as far as the moon. As to the stars properly so-called, they lie at distances almost incomparably more remote than the planets. You therefore see how justly we may describe the' moon as our neighbour when it is compared with the other bodies of the universe. The relative distances of France and Japan from England may be likened to the distances of the moon and the nearest of the other heavenly bodies from this earth. We thus have the opportunity of seeing the moon much more favourably than any of the other heavenly bodies. For it is obvious that the nearer such an object is, t^e better we can observe- it. A feature on the surface of a planet that would be wholly invisible from our earth might nevertheless be large enough to show as a conspicuous object if it were placed on the moon. - But- though the moon is so near us when compared with the-othcr heavenly bodies, it is still a very long way off when estimated by more ordinary standards. Under the most favourable circumstances our neighbour is nearly a quarter of a million miles away, and when viewed from so great a distance objects have to be of consideiablc magnitude if they are to be visible at all. A lunar mountain, even if it were as great as Mont Blanc itself, would only be shown like a tiny hillock by our mightiest telescopes. No object on the moon could be seen unless it were at least as large as a Town Hall or a Cathedral. Were the great Pyramid of Egypt on the moon, it would only seem to us as a speck which an artist who was making a sketch at the telescope would indicate by a dot with his pencil. In our study of the geography of the moon, we need, therefore, not expect to see anything clearly, except the broad features of its scenery. Here, fortunately, we enjoy an advantage which -an. astronomer who dwelt on the moon would not have if.he endeavoured to look at the earth. The surface of our globe is so extensively obscured by clouds that it would-be very hard for a lunar inhabitant to obtain. Such a viaw of this globe as to gain any adequate idea of what its surface was really like ; here and theie no doubt he mi«;ht get an occasional glimpse, but it is uncertain to what extent a knowledge of the geography of the earth could be obtained by an examination conducted from a point of view lying beyond our atmospheie. The moon, strange to say, has no encompassing sheets of cloud ; there is, indeed, little or no air there, and consequently whenever our own sky will permit us to see through it there is no other obstacle to our obtaining a clear view of the moon. There are certain spots or marks on the moon as seen with the unaided eye with which everyone is familiar. They can be best observed when the moon is full, and it is a remarkable fact that the featuies exhibited by the full moon are always the same. In fact, the moon always turns the same face to us, we are never granted a glimpse at the other side, and as to what that other side may be like neither I nor anyone else can give, you the slightest information. The diameter of the moon is about 2,000 miles, from whicli 1 we infer that .theJicrai,;, sphere which we do see has an- area about; double ,,jarf r -big. as, the entire of "ifiuTrope." Some of-, those large spots whiuh form the* features' on tn'e full moon are, therefore,about as large as France or Spain. These regions have a different colour to the rest of the moon's surface, and the telescope shows that their floors are smoother than other tracts of lunar country. We have good reason to believe that these dark patches indicate the basins of great seas that once covered a considerable part of the moon's service.. In fact, the very names by which astronomers distinguish these objects involve this doctrine. Thus we speak of the Mare Serenitatis as the name of a region where a Pacific ocean is once supposed to have reposed. We are, however, certain that the burface of the moon no longer contains any visible water. It seems to have penetrated into the interior of the lunar globe at some period ages before telescopes were ever directed to the heaven?. Though the ancient sea-basins are the only conspicuous objects in the naked-eye view of the moon, yet when the telescope is used these features are not nearly so interesting as the craters. These are multitudes of small objects quite invisible to the unaided eye, though many of them must be a hundred miles or more in diameter. To observe these objects with advantage we should, select an opportunity when the moon is at or near t'.ie quarter. In any case we .should avoid making our vUit to the observatory at the time when the moon is full. You must remembei that the moon derives its litrht from the sun just as the earth does. The sun illuminates that half of the moon which happens to be turned towards it, while the other half in in darkness, and accordingly as we see more or less of the bright half we see the moon

more or le?s full. It is along the diameter of the moon at the quarter, or at any time \ along the boundary between the bright part and the dark, chit the illumination is best suited for rendering faint objects visible. There the feature^ are shown with that relief which can alono be obtained by strong contrasted light and shade. Thei-3 is ono particular kind of object which specially charactoiise^ the geography of the moon. The type of this object is a ring, and of these rings thero aio hundreds. They have been most carefully drawn on the charts of the moon, and indeed the great majority have had special names assigned to them. Lot me try to desciibe what one of these rings would ac'ually look like if you were able to stand on the moon. You would find the ring to be a rampart of lofty mountains, surrounding a rough and rugged interior. The diameter of this circle will range from the smallest size that we can just discern, which will be a few bundled yaids across, up to vast' extents of 100 miles, or even more, in diameter; indeed, if you were standing in , the centre of one of the larger of these rings the range of mountains which enciicled it would be invisible to you, because they would lie below your horizon. Our bird's eye view of the moon gives us almo-t a better glance at the general features ot these objects than you could obtain by actually going there. Sometimes there is. a lofty mountain peak rising in the. centre .of ' the ring, and oftetVtimes the con tour >af the ring is broken by the invasion of other rings of varying sizes. While the^e aic the general features of the moon's geography, some others may be noted. There aje, for example, lofty ranges of mountains which, in their altitude and in their massheness, may to compaied' with our Alps or our Appennines, names which, indeed, have been also applied with appropriateness to corresponding lunar objects. 1 imagine, however, that a walk on the moon would be attended with most frightful diih'culties from the nature of its surface alone, quite independently of other impediments of a still more insuperable cles cription. The entire of moon-land appeals to be an utter desert, a desert, too, not of sand, bub of rough and rugged rocks, carved into the wildest forms, and presenting every difficulty to one who should try to move across such a country. .Lilliputians trying to run races over a heap of bricks would, 1 fancy, have an easy task of it as compared with the. Conditions under which you or I would try to walk upon the moon. You know how in climbing over an Alpine glacier the piesoncc of a yawning crevasse is a dithoulty which sometimes battles the mountaineer. The lunar ramblci will find his way occasionally barred by a fearful chasm half a mile or more in width, descending to a depth which his eye cannot fathom. Never in the course ot his travels will he meet with any features resembling those with which he is happily familiar on the- earth. He will never meet with a, brook or a ri\er, he will never &cc a grassy field or a tree"; in fact, water being now entirely absent irom the moon, it is almost needless to add that vegetation "ot< any sorb is not to be found* there .either." It follows also that there can be no animal life on the moon, for every animal we Unow' of contains water as a part of its organisation, anc" unless there can be beings in whose veins run.^ quicksihei instead ot blood there seems no possibility of animated existence on our satellite.