The great Herschel
claimed that the planet was so enveloped in vapor or clouds that
no permanent features could be seen on its surface. The best
equipped recent observers think they see faint, shadowy patches,
which remain the same from day to day, and which show that the
planet always presents the same face to the sun, as the moon does
to the earth. Others do not accept this conclusion as proved,
believing that these patches may be nothing more than variations
of light, shade, and color caused by the reflection of the sun's
light at various angles from different parts of the planet.
There is also some mystery about the atmosphere of this planet.
When Venus passes nearly between us and the sun, her dark
hemisphere is turned towards us, her bright one being always
towards the sun. But she is not exactly on a line with the sun
except on the very rare occasions of a transit across the sun's
disk. Hence, on ordinary occasions, when she seems very near on a
line with the sun, we see a very small part of the illuminated
hemisphere, which now presents the form of a very thin crescent
like the new moon. And this crescent is supposed to be a little
broader than it would be if only half the planet were illuminated,
and to encircle rather more than half the planet.
Pages:
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38