In the reading passage, there is ample support for the
author’s claim that some plausible causes of the ashen light of Venus have been
found. However, the lecturer in the lecture gives several reasons as a rebuttal
to the author’s point.
First, the lecturer contends that it is impossible
that a chemical process is responsible for the ashen light. The light produced
in this way would be so faint that it could only be observed with powerful
telescopes. However, the ashen light was seen using simple telescopes. This casts
doubt on the reading passage’s claim that a chemical process causes this
phenomenon.
Next, the lecturer asserts that it is unlikely that
the ashen light is sunlight reflected off cloud. This is because the ashen
light happens very rarely, yet there is constant sunlight on Venus. The ashen
light would be detected more often if the source were sunlight.
Finally, the lecturer points out that it cannot be
true that aurorae are the ashen light. Plasma only enters planet’s atmosphere
when it is drawn in by a magnetic field. However, as Venus does not have one,
there is no way that aurorae can occur on Venus. This refutes the reading
passage’s claim that the glow observed on Venus may be aurorae.