To this I shall answere out of Galilæus.
1. You must know that there is not meerely one ranke of mountaines about the edge of the moone, but divers orders, one mountaine behind another, and so there is somewhat to hinder those void spaces which otherwise, perhaps, might appeare.
Now where there be many hils, the ground seemes even to a man that can see the tops of all. Thus when the sea rages, and many vast waves are lifted up, yet all may appeare plaine enough to one that stands at the shore. So where there are so many hils, the inequality will be lesse remarkable, if it be discerned at a distance.
2. Though there be mountains in that part which appeares unto us, to be the limbe of the Moone, as well as in any other place, yet the bright vapours hide their appearance: for there is an orbe of thicke vaporous aire that doth immediatly compasse the body of the Moone, which though it have not so great opacity, as to terminate the sight, yet being once enlightened by the Sunne, it doth represent the body of the Moone under a greater forme, and hinders our sight from a distinct view of her true circumference. But of this in the next Chapter.
I have now sufficiently proved, that there are hills in the Moone, and hence it may seeme likely that there is also a world, for since providence hath some speciall end in all its workes, certainly then these mountaines were not produced in vaine, and what more probable meaning can wee conceive there should be, than to make that place convenient for habitation.
Proposition 10.
That there is an Atmo-sphæra, or an orbe of grosse vaporous aire, immediately encompassing the body of the Moone.
As that part of our aire which is neerest to the earth, is of a thicker substance than the other, by reason tis alwaies mixed with some vapours, which are continually exhaled into it. So is it equally requisite, that if there be a world in the Moone, that the aire about that should be alike qualified with ours. Now, that there is such an orbe of grosse aire, was first of all (for ought I can reade) observed by Meslin, afterwards assented unto by Keplar and Galilæus, Vide Euseb. Nierem. de Nat. Hist. l. 2. c. 11. and since by Baptistae Cisatus, Sheiner with others, all of them confirming it by the same arguments which I shall onely cite, and then leave this Proposition.
1. ’Tis observed, that so much of the Moone as is enlightened, is alwaies part of a bigger circle then that which is darker. Their frequent experience hath proved this, and an easie observation may quickely confirme it. But now this cannot proceede from any other cause so probable, as from this orbe of aire, especially when we consider how that planet shining with a borrowed light, doth not send forth any such rayes as may make her appearance bigger then her body.
2. ’Tis observed in the Solary eclipses, that there is a great trepidation about the body of the Moone, from which we may likewise argue an Atmo-sphæra, since we cannot well conceive what so probable a cause there should be of such an appearance as this, Quod radii Solares à vaporibus Lunam ambientibus fuerint intercisi, Scheiner. Ros. Vrs. l. 4. pars 2. c. 27. that the Sun beames were broken and refracted by the vapours that encompassed the Moone.