This atmosphere of ours is the most influential element in beautifying our terrestrial scenery, and the absence of such an appendage from the moon is the great modifying cause that affects lunar scenery as compared with that of the earth. We are accustomed to the sun with its dazzling brightness—overpowering though it be—subdued and softened by our vaporous screen. Upon the moon there is no such modification. The sun’s intrinsic brilliancy is undiminished, its apparent distance is shortened, and it gleams out in fierce splendour only to be realised, and then imperfectly, by the conception of a gigantic electric light a few feet from the eye. And the brightness is rendered the more striking by the blackness of the surrounding sky. Since there is no atmosphere there can be no sky-light, for there is nothing above the lunar world to diffuse the solar beams; not a trace of that moisture which even in our tropical skies scatters some of the sun’s light and gives a certain degree of opacity or blueness, deep though it be, to the heavens by day. Upon the moon, with no light-diffusing vapour, the sky must be as dark or even darker than that with which we are familiar upon the finest of moonless nights. And this blackness prevails in the full blaze of the lunar noon-day sun. If the eye (upon the moon) could bear to gaze upon the solar orb (which would be less possible than upon earth) or could it be screened from the direct beams, as doubtless it could by intervening objects, it would perceive the nebulous and other appendages which we know as the corona, the zodiacal light, and the red solar protuberances: or if these appendages could not be viewed with the sun above the horizon they would certainly be seen in glorious perfection when the luminary was about to rise or immediately after it had set.
And, notwithstanding the sun’s presence, the planets and stars would be seen to shine more brilliantly than we see them on the clearest of nights; the constellations would have the same configurations, though they would be differently situated with respect to the celestial pole about which they would appear to turn, for the axis of rotation of the moon is directed towards a point in the constellation Draco. The stars would never twinkle or change colour as they appear to us to do, for scintillation or twinkling is a phenomenon of atmospheric origin, and they would retain their full brightness, down even to the horizon, since there would be no haze to diminish their light. The planets, and the brighter stars at least, would be seen even when they were situated very near to the sun. The planet Mercury, so seldom detected by terrestrial gazers, would be almost constantly in view during the lunar day, manifesting his close attendance on the central luminary by making only short excursions of about two (lunar) days’ length, first on one side and then on the other. Venus would be nearly as continuously visible, though her wanderings would be more extensive on either side. The zodiacal light also, which in our English latitude and climate is but rarely seen and in more favourable climes appears only when the sun itself is hidden beneath the horizon, would upon the moon be seen as a constant accompaniment to the luminary throughout his daily course across the lunar sky. The other planets would appear generally as they do to us on earth, but, never being lost in daylight, their courses among the stars could be traced with scarcely any interruption.