The question whether Venus is habitable is discussed by an astronomical correspondent in the "Manchester Guardian It is somewhat of a paradox that, while our knowledge of the distant suns and clusters of suns on the confines of infinity has gone forward in recent years by leaps and bounds, the condition of our nearest planetary neigh-hour has been more or less enwrapped in mystery. With the single exception of the moon—which is our earth's peculiar possession, a "detached continent."" in the picturesque phrase of Flammarion—Venus approaches the earth more closely than any body of planetary dimensions. When the two planets are at their nearest they are separated by about 26 millions of miles, which is, cosmically speaking, but a stone's-throw.
in these occasions of closest ap-; proach, however, we cannot see Venus at all. For, like the earth, the "evening star" is a dark body shining with reflected sunlight, and when the two sister worlds are nearest Venus turns its dark side towards us and is totally invisible except on those rare ocean sions of "transit of Venus," when the planet appears like a_ little black spot traversing the glowing dise of the sun. We cannot, therefore, see Venus at minimum distance. This is the first disadvantage under which astronomers have to labour in the study of our neighbour world. The second disadvantage is that we never see the disc fully illuminated. Unlike Mars, whose orbit encloses that of the earth, Venus revolves in a pathway within that of our world. And, as has been already said, Venus is invisible when_ between the earth and the sun. It is also lost to view when at the other side of the sun, at its maximum distance. Accordingly astronomers have to content themselves with observing the planet during its various phases.
These obstacles to the study of the planet would be serious enough in themselves, but there is a third which is more formidable still, and that is the dazzling brightness of Venus. Our neighbour world reflects fully 92 per cent. of the total sunlight which falls upon it; indeed it has the greatest re-reflective capacity of all the planets. The precise cause of this high reflective power is not known with certainty. The prevailing view has hitherto been that the planet is enveloped by the dense cloud laden atmosphere—the _refective capacity of cloud being very great,—but the late Professor Lowell maintained that the planet's brilliance was due to the presence of much fine dust in a comparatively transparent atmosphere, Whatever the cause, the result is that the markings on Venus are elusive, hazy, and ill-defined. Consequently, there has been nothing like certainty even about such matters as the length of the pla-
Text read from the printed page and cleaned; old type leaves the occasional error.