St Valentine, whose day was yesterday, was not the first divinely-appointed custodian of affaires de coeur. His predecessor in classical times was Venus, goddess of love and mother of the mischievous and scheming Cupid. As star-crossed lovers gaze at her planet in the evening sky, they might well imagine their Utopia - a romantic world of everlasting spring and rose-red sunsets. Reality, alas, takes no account of lovers' dreams; Venus is, in fact, a hellish spot.
The planet is similar in size to Earth, but it revolves more slowly on its axis so that a Venusian day is 243 times longer than is ours. The surface is a dry rocky plain, sweltering under a dull orange sky. The atmosphere is composed almost entirely of carbon dioxide; it is very dense, so that the average barometric pressure is a massive 90,000 hectopascals, 90 times that which we experience here on Earth.
Being closer to the sun, Venus receives almost twice as much solar energy as Earth. Moreover, the CO2 traps a great deal of this heat by means of a massive "greenhouse effect", so the surface temperature of the planet is some 470 C, hot enough to melt tin and lead, and to boil mercury. This very high temperature, and many other factors as well, make plant life of any kind impossible, completing a vicious circle whereby there is no mechanism on the planet for reducing the amount of CO2.
Another remarkable feature of Venus is that it is completely enveloped in an unbroken layer of dull yellowish cloud some 25 miles above the ground, which, rather unpleasantly, consists almost entirely of tiny droplets of concentrated sulphuric acid. Below the cloud the atmosphere is clear; there are no storms or weather changes, just an incredible and all-pervasive heat. Winds are gentle, but because of its very dense atmosphere, even a gentle Venusian breeze has the destructive force of the worst of any of our earthly hurricanes.
In the unlikely event of any human being ever standing in the dim twilight on the scorching surface of the planet Venus, he or she would be crushed by its heavy atmosphere of unbreathable gases, and simultaneously exposed to a slow persistent drizzle of sulphuric acid. The experience might be aptly recorded in the words of Milton's Paradise Lost:
A dungeon horrible, on all sides round
As one great furnace flam'd; yet from those flames
No light - but rather darkness visible
Serv'd only to discover sights of woe.
Or as Jean Paul Sartre might well have said, were he not so preoccupied with other people: l'Enfer, c'est Venus.