Broca's Brain - Carl Sagan [65]
The true situation is very different, as we have seen. Neither Mariner 2 nor any subsequent investigation of the Venus atmosphere has found evidence for hydrocarbons or carbohydrates, in gas, liquid or solid phase. It is now known (Pollack, 1969) that carbon dioxide and water vapor adequately fill the 3.5 micron window. The Pioneer Venus mission in late 1978 found just the water vapor needed, along with the long-observed quantity of carbon dioxide, to account for the high surface temperature through the greenhouse effect. It is ironic that the Mariner 2 “argument” for hydrocarbon clouds on Venus in fact derives from an attempt to rescue the greenhouse explanation of the high surface temperature, which Velikovsky does not support. It is also ironic that Professor Kaplan was later a co-author of a paper that established a very low abundance of methane, a “petroleum gas,” in a spectroscopic examination of the Venus atmosphere (Connes, et al., 1967).
In summary, Velikovsky’s idea that the clouds of Venus are composed of hydrocarbons or carbohydrates is neither original nor correct. The “crucial test” fails.
PROBLEM VIII
THE TEMPERATURE OF VENUS
ANOTHER CURIOUS circumstance concerns the surface temperature of Venus. While the high temperature of Venus is often quoted as a successful prediction and a support of Velikovsky’s hypothesis, the reasoning behind his conclusion and the consequences of his arguments do not seem to be widely known nor discussed.
Let us begin by considering Velikovsky’s views on the temperature of Mars (pages 367–368). He believes that Mars, being a relatively small planet, was more severely affected in its encounters with the more massive Venus and Earth, and therefore that Mars should have a high temperature. He proposes that the mechanism may be “a conversion of motion into heat,” which is a little vague, since heat is precisely the motion of molecules or, much more fantastic, by “interplanetary electrical discharges” which “could also initiate atomic fissions with ensuing radioactivity and emission of heat.”
In the same section, he baldly states, “Mars emits more heat than it receives from the Sun,” in apparent consistency with his collision hypothesis. This statement is, however, dead wrong. The temperature of Mars has been measured repeatedly by Soviet and American spacecraft and by ground-based observers, and the temperatures of all parts of Mars are just what is calculated from the amount of sunlight absorbed by the surface. What is more, this was well known in the 1940s, before Velikovsky’s book was published. And while he mentions four prominent scientists who were involved before 1950 in measuring the temperature of Mars, he makes no reference to their work, and explicitly and erroneously states that they concluded that Mars gave off more radiation than it received from the Sun.
It is difficult to understand this set of errors, and the most generous hypothesis I can offer is that Velikovsky confused the visible part of the electromagnetic spectrum, in which sunlight heats Mars, with the infrared part of the spectrum, in which Mars largely radiates to space. But the conclusion is clear. Mars, even more than Venus, by Velikovsky’s argument should be a “hot planet.” Had Mars proved to be unexpectedly hot, perhaps we would have heard of this as a further confirmation of Velikovsky’s views. But when Mars turns out to have exactly the temperature everyone expected it to have, we do not hear of this as a refutation of Velikovsky’s views. There is a planetary double standard at work.
When we now move on to Venus, we find rather similar arguments brought into play. I find it odd that Velikovsky does not attribute the temperature of Venus to its ejection from Jupiter (see Problem I, above), but he does not. Instead,