She has, however, a far more splendid Sun than ours--the very same Sun only much nearer, and bigger and more dazzling. She also has in her sky a very exquisite little shining Earth, far lovelier than Venus at her best ever appears to us. And I will tell you why. Venus comes at times nearer to our Earth than any other world in all the sky, except our Moon. If the Moon is our little Sister-World Venus is our Next-Door Neighbor. When the Earth happens to be on one side of the Sun and Venus on the other side the two then are widely parted. When both are on the same side of the Sun at once they are quite near--divided by only about twenty-six millions of miles. Of course twenty-six millions of miles sound a good deal to you and me. We think so much of even one thousand miles on the Earth, and one million is a thousand thousand. But in talking of sky-distances twenty-six millions of miles are merely a matter of next-door neighbors! Unfortunately, when Venus is at her nearest to us we cannot see her. She is then, like our Moon at New-Moon, between us and the Sun, so that her dark side is toward us, and her bright side is away from us. This is a great pity, because she would be a lovely sight then, so near and brilliant. Our best sight of her is when she is away to one side, and then it is really only “Half-Venus” that we see. Even that half is the brightest of all heavenly bodies to us, after the Sun and Moon; but you can fancy how much more beautiful the whole would be. We do see the whole of her when she gets right beyond the Sun; but then she is so very, very far away that she becomes much more small and dim. However, when Venus is New-Venus to us--like the Moon being New-Moon--our Earth is Full-Earth to Venus. Then indeed our Earth must be a splendid sight, if only there were anybody on Venus to admire her! When Venus comes between us and the Sun she is more commonly not _exactly_ between. Now and then, however, instead of being a little higher or lower, she is just precisely between, and so we have a Transit of Venus. It is much the same as a Transit of Mercury. Only the round black dot is bigger, and can be seen more easily; sometimes even without a telescope. Two transits of Venus come near together, within a few years. Then for more than a hundred years there is no transit; after which two more come again. Venus can never see a transit or passing of our Earth over the Sun, because the pathway of the Earth lies outside the pathway of Venus. So our Earth can never pass between Venus and the Sun. But Venus can see a transit of Mercury; and we on Earth can see transits of Mercury and Venus. And Mars doubtless can see transits of Mercury, Venus and Earth, though the Earth can never see a transit of Mars. It is always an _outer_ planet which sees an _inner_ planet seem to pass across the Sun’s face. In all these cases, if the worlds were very near together--as near as our Moon is to the Earth--the Transits would be Eclipses.