The lecturer contends that the three
theories in the reading passage about the reason for the ashen light of Venus
cannot explain the reason very well, so the reason of the light is still
mysterious. This casts doubt on the reading passage’s claim that a lot of
possible sources of the ashen light of Venus have been identified.
To begin with, the lecturer asserts that a chemical
process in Venus’s atmosphere cannot be the reason for the ashen light. This is
due to the fact that the light which is produced when carbon monoxide and
oxygen recombine to form carbon dioxide is so faint that it cannot be watched
by simple telescopes that astronomers use but only by strong telescopes. This
counters the argument made by the author that it is possible that a chemical
process in Venus’s atmosphere result in the ashen light of Venus.
On top of that, the lecturer maintains that
it is unlikely that sunlight reflected off clouds is the reason for the ashen
light of Venus. If the light is made by sunlight reflection, the light has to
be seen more often because of the stability of sunlight. However, the ashen
light can be rarely watched. This contradicts the claim in the reading passage
that the ashen light of Venus can be the result of sunlight reflection.
Lastly, the lecturer insists that the
theory that the ashen light is aurorae is not true. This is attributed to the
fact that there is no magnetic field around the Venus. As far as the fact that collisions
between plasma from the Sun and magnetic field around the planet create aurorae
is concerned, there cannot be aurorae on Venus. This refutes the argument of
the author that the glow on Venus can be aurorae.