Venus



""Observation: You couldn't see a thing. Conclusion: Dinosaurs.""

- Carl Sagan, describing what Venus's cloud cover did for fiction

The second planet from the sun, and the closest planetery orbit to the Earth's. As seen from the Earth, it's often the brightest point of light in the night sky -- in fact, if you know where to look, it can sometimes be seen even in full daylight. This brightness is partly due to how close it gets to the Earth, and partly due to its bright whitish cloud cover. Interestingly, Venus appears brightest when it's in its crescent phase, because it's much closer to the Earth at that point that it is when it's in its gibbous phase. (Venus can't be seen when it's full, of course, since the sun is smack-dab between the Earth and the planet at that point.) Since Venus is never more than 40-some-odd degrees away from the Sun, it's most prominent right after sunset or right before sunrise, giving it the names "evening star" and "morning star."

Venus used to be called "Earth's twin". It's 95% as big around as the Earth, it's got 90% of Earth's surface gravity, it's got an atmosphere with clouds in it, it's about the same distance from the sun -- what could be so different?

Well, for one, its surface temperature turned out to be nearly 900 degrees Fahrenheit, hotter than a self-cleaning oven. The "air" consists almost entirely of carbon dioxide, and at the surface the pressure is equal to being half a mile under the ocean on Earth. And those clouds? They're not made of water vapor, they're made of sulfuric acid.

These rather depressing details were revealed by the Soviet Venera space probes, sent to the planet in the late 1960s. Before that time, many Science Fiction authors held out hope that Venus might harbor life.

Its surface features, long hidden under the constant cloud cover, were finally mapped by the Magellan space probe using radar in the 1990s. The highest mountain is Maxwell Montes, almost 7 miles above the average surface level. If you stood on its peak, it'd be a downright chilly 380°C / 716°F, and a mere 60 atmospheres of pressure. The culprit for all this heat is the greenhouse effect -- Earth's atmosphere is less than 1% carbon dioxide, while Venus's is over 90% carbon dioxide. Earth started with the same amount, but it ended up trapped in carbonate rock. Venus also started with the same amount of water as the earth had, but it remained in vapor form (300 atmospheres worth) and created a super greenhouse effect with temperatures in the thousands of degrees. Eventually the water molecules dissociated into hydrogen and oxygen and escaped into space, leaving Venus high and dry. Due to Venus being mythologically associated with femininity, by convention all geographic features there are named after women or female entities, except for Maxwell Montes and Alpha and Beta Regio. There is some argument over whether the proper adjective is 'Venusian', 'Venerean', or 'Cytherean'.

At some point in the planet's early history, some big huge honkin' planetesimal struck it at an oblique angle, causing it to rotate very slowly backwards when compared with all the other planets in the Solar system. As a result of this super-slow rotation, a Venusian solar day is nearly as long as a Venusian year. Not that you'd be able to see much difference between day and night while on the surface. The super-thick atmosphere bends light so severely that the horizon appears to curve upward, allowing you to see all the way around the planet. Twice. Whether you're on the day side or the night side, you'll see a hazy overcast sky that's about the same brightness everywhere -- assuming you survive the lack of oxygen, the crushing pressures, and the hellish temperatures, that is.

Well, now some optimistic stuff about Venus. There is a layer in its atmosphere where both temperature and pressure are Earthlike, located some 60 kilometers above the surface. The only non-earthlike thing in this habitability zone is atmospheric chemistry, which is mostly CO2 with some sulfuric acid vapors; but it also means that normal Earth air will work in this atmosphere like a lifting gas, easily supporting a Cloud City.

And as we all know from pop-psychology, women are from there.

Pre-Venera

 * Abbott and Costello Go to Mars, despite its title, has the comic duo meet space women on Venus.
 * First Spaceship On Venus
 * The alien in It Conquered the World came from Venus, hitching a ride to Earth on one of our military space probes.
 * Immanuel Velikovsky proposed, based on his reading of certain ancient mythology, that Venus was originally spat out of Jupiter, and wandered through the inner solar system causing the parting of the Red Sea and Joshua 10:13's sun-standing-still-in-the-sky episode, before settling into its current near-circular orbit.
 * In Lucky Starr and the oceans of Venus by Isaac Asimov, Venus is an ocean planet with seas and kelp (and domed underwater cities).
 * The Arthur C Clarke short story "Before Eden" (1961) recounts the tales of the first astronauts to land on Venus, who discover a carpet-like creature living there. They take pictures, then drop off their waste products and blast off. Unbeknownst to them, the creature finds their waste delectable, but has no immunity to the Earth bacteria within it and soon spreads deadly Earth germs to its entire species, wiping them all out.
 * In Robert Heinlein's Space Cadet, the titular cadets answer a Venusian Distress Call. Venus is depicted as the typical swamp planet of the pre-Venera wishful-thinking days.
 * In CS Lewis's Perelandra, Venus is a garden of Eden where original sin never occurred.
 * In the Disney film Mars and Beyond, one scene has the narrator describe the conditions of the other planets in the Solar System besides Mars, and when he gets to Venus he says "There may be life on Venus..."
 * An episode of The Twilight Zone features a man from Mars who gives Super Strength to an earthman to see what he'll do with it. The earthman squanders his abilities, so the Martian brags about how pathetic Earthmen are to a patron in an Earth bar. It turns out the man listening to him is from Venus, and the Venusians are about to invade and conquer both Mars and Earth.
 * An early 1950s episode of X Minus One uses the exact same plot.
 * The 1957 B Movie 20 Million Miles to Earth features a spaceship freshly returned from Venus that crashes into the sea near Italy. It turns out to be carrying a Venusian embryo which, predictably, grows up into a giant reptilian monster that terrorizes Rome.

Post-Venera
"'When I was about eight years old, I was watching the sunset, and I asked my dad, "What’s that bright star over there?", and he said that it wasn’t really a start at all, but it was actually a whole planet called Venus. [points at the sky] Which should be over there soon. He said, "You know why they called it Venus? Because they thought it was so beautiful and glowing. And what they didn’t know is that it was filled with deadly gases and sulfuric acid rain," and I thought, This is it, I’m hooked.'"
 * In Contact, Dr. Arroway tells her preacher beau that Venus was what convinced her to become an astronomer:


 * An episode of The Six Million Dollar Man features a space probe engineered to survive on the surface of Venus. It accidentally went back to Earth and embarked on a rampage of destruction.
 * Charles Stross's Saturn's Children starts out in a city floating in Venus's atmosphere, then follows its Fem Bot protagonist through the rest of The Solar System
 * Interplanet Janet split for Venus, but on Venus she found she couldn't see a thing for all the clouds around.
 * An episode of Cosmos named "Heaven and Hell" features Earth and Venus in the title roles. Venus, according to Carl Sagan, is the one planet in the solar system most like Hell.