One may well envy those who have had the good fortune to
behold this spectacle--to actually see, as it were, the air that the
inhabitants of another world are breathing and making resonant with all
the multitudinous sounds and voices that accompany intelligent life. But
perhaps some readers will prefer to think that even though an atmosphere
is there, there is no one to breathe it.
[Illustration: VENUS'S ATMOSPHERE SEEN AS A RING OF LIGHT.]
As the visibility of Venus's atmosphere is unparalleled elsewhere in the
solar system, it may be worth while to give a graphic illustration of
it. In the accompanying figure the planet is represented at three
successive points in its advance toward inferior conjunction. As it
approaches conjunction it slowly draws nearer the earth, and its
apparent diameter consequently increases. At _A_ a large part of the
luminous crescent is composed of the planet's surface reflecting the
sunshine; at _B_ the ratio of the reflecting surface to the illuminated
atmosphere has diminished, and the latter has extended, like the curved
arms of a pair of calipers, far around the unilluminated side of the
disk; at _C_ the atmosphere is illuminated all around by the sunlight
coming through it from behind, while the surface of the planet has
passed entirely out of the light--that is to say, Venus has become an
invisible globe embraced by a circle of refracted sunshine.
We return to the question of life.
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