Worlds in Collision
Tim Callahan, religion editor of "Skeptic", presses the case further in claiming that the composition of the atmosphere of Venus is a complete disproof of "Worlds in Collision". "...Velikovsky's hypothesis stands or falls on Venus having a reducing atmosphere made up mainly of hydrocarbons. In fact, the atmosphere of Venus is made up mainly of carbon dioxide—carbon in its "oxidized" form—along with clouds of sulfuric acid. Therefore, it couldn't have carried such an atmosphere with it out of Jupiter and it couldn't be the source of hydrocarbons to react with oxygen in our atmosphere to produce carbohydrates. Velikovsky's hypothesis is falsified by the carbon dioxide atmosphere of Venus."
Vacuum airship
where formula_28 formula_29 and formula_30 formula_31 are pressure and density of standard Earth atmosphere at sea level, formula_32 and formula_33 are molar mass (kg/kmol) and temperature (K) of atmosphere at floating area.
Of all known planets and moons of the Sun system only the Venusian atmosphere has formula_21 big enough to surpass formula_20 for such materials as some composites (below altitude of ca. 15 km) and graphene (below altitude of ca. 40 km). Both materials may survive in the Venusian atmosphere. The equation for formula_21 shows that exoplanets with dense, cold and high-molecular (formula_37, formula_38, formula_39 type) atmospheres may be suitable for vacuum airships, but it is a rare type of atmosphere.