Venus. April 12, 1909, 3h 26m—4h 22m—by Dr. Lowell.
The years that have passed since these observations were made have brought corroboration of them. Several observers at Flagstaff have seen and drawn them and added discoveries of their own, among whom are especially to be mentioned, of the observatory staff: Miss Leonard, Dr. Slipher, and Mr. E. C. Slipher.[7]
In character these markings were peculiar and distinctive. In addition to some of more ordinary character were a set of spokelike streaks which started from the planet’s periphery and ran inwards to a point not very distant from the centre. The spokes started well-defined and broad at the edge, dwindling and growing fainter as they proceeded, requiring the best of definition for their following to their central hub.
The peculiar symmetry thus displayed, a symmetry associated with the planet’s sunrise and sunset line, or, strictly speaking, what would be such did the Sun for Venus ever rise or set, would seem inexplicable, except for that very association. When we reflect, however, upon what this means, a very potent cause for them becomes apparent, so potent that surprise is turned into appreciation that nothing else could well exist. That Venus turns on her axis in the same time that she revolves about the Sun, in consequence of which she turns always the same face to him, must cause a state of things of which we can form but faint conception, from any earthly analogy. One face baked for countless æons, and still baking, backed by one chilled by everlasting night, while both are still surrounded by air, must produce indraughts from the cold to the hot side of tremendous power. A funnel-like rise must take place in the centre of the illuminated hemisphere, and the partial vacuum thus formed would be filled by air drawn from its periphery, which, in its turn, would draw from the regions of the night side. Such winds would sweep the surface as they entered, becoming less superficial as they advanced, and the marks of their inrush might well be discernible even at the distance we are off. Deltas of such inroad would thus seam the bounding circle of light and shade.
I
Showing convection currents in the planet’s atmosphere.
