"How long is her day?" Smith wanted to know.
"Can't say. Some observers claim to have seen her clearly enough to announce a day of the same length as ours. Others calculate that she's like Mercury; always the same face toward the sun. If so, her day is also her year—two hundred and twenty-five of our days."
Van Emmon looked disappointed. "In that case she would be blistering hot on one side and freezing cold on the other; except," remembering Mercury, "except for the 'twilight zone,' where the climate would be neither one nor the other, but temperate." He pointed to the line down the middle of the disk before them, the line which divided the lighted from the unlighted, the day from the night.
The four looked more intently. It should be remembered that the very brilliance of Venus has always hindered the astronomers; the planet as a whole is always very conspicuous but its very glare makes it impossible to see any details. The surface has always seemed to be covered by a veil of hazy, faintly streaked vapor.
Smith gave a queer exclamation. For a moment or two he stared hard at the planet; then looked up with an apologetic grin.
"I had a foolish idea. I thought—" He checked himself. "Say, doesn't Venus remind you of something?"
The doctor slowly shook his head. "Can't say that it does, Smith. I have always considered Venus as having an appearance peculiarly her own. Why?"
The engineer started to answer, stopped, thought better of it, and instead pointed out the half that was in shadow. "Why is it that we can make out the black portion so easily?"
Kinney could answer this. "The fact is, it isn't really black at all, but faintly lighted. Presumably it is star-shine."
"Star-shine!" echoed the architect, interested.