Extraterrestrial atmosphere reaching 70 m/s or more in the upper troposphere. The stratosphere and mesosphere extend from 65 km to 95 km in height. The thermosphere and exosphere begin at around 95 kilometres, eventually reaching the limit of the atmosphere at about 220 to 250 km. The air pressure at Venus' surface is about 92 times that of the Earth. The enormous amount of CO in the atmosphere creates a strong greenhouse effect, raising the surface temperature to around 470 °C, hotter than that of any other planet in the Solar System. The Martian atmosphere is very thin and composed mainly of
A Planet Called Utopia same reason), and temporary personal relationships favored. Diseases are nonexistent, and cures have been found for all of them. Life involves pleasure and adventure (skiing, scuba diving, parachuting, automobile racing) all day long. The population nevertheless needs an occasional birth, so couples are allowed to have children according to a lottery system, such that the number of births is exactly equal to the number of accidental deaths in a year. The protagonist, Hardy Cronyn, is the first off-worlder to be allowed onto the planet in sixty years. A lot of diplomatic arm wrestling led to the planet's agreement to let