from the book, "Petrified Lightning"
"We can learn even from nightmares."
Earth is about 93 million miles from the sun; approximately 26 million miles nearer to the sun is the planet Venus. Originally named for the Roman goddess of love and beauty, Venus was until quite recently identified principally as the morning and evening star because it is brilliant enough to be seen brightly even when the sky is still partially lit by the sun. Being closer to Earth than any other planet, Venus naturally appears very bright, but the dense cover of white clouds that cloaks the planet and glares in the light of the sun contributes more to its brilliance.
When Galileo first gazed at Venus with his newly devised telescope he could tell it was a sphere because it waxed and waned in phases, from crescent to a full circle, just as the moon did. He could see nothing of its surface features, however, and for the next three centuries no astronomer saw any more than Galileo did. Science fiction writers were free to dream up Venus as an imaginary paradise. Astrophysicists could reason, with merciless logic, that the oceans and atmosphere of Venus were laced with valuable oils and that this was a watery, very livable planet. As long as the cloud cover kept the surface a mystery, even researchers equipped with the most powerful telescopes were forced to guess and imagine.
Venus is so similar to Earth in size and weight, and in its chemical elemental makeup that referring to the planet as Earth's twin was quite natural. A pronounced difference between Venus and Earth is their rotation. Venus takes 243 earth days to complete one rotation (one "day"), which is remarkably sluggish for a planet. Also, its rotation is retrograde, with the sun rising in the west and setting in the east. Scientists believe that Venus may have had a normal rotation during its primeval days but some eons ago suffered a titanic collision with another celestial body that sent the planet reeling backward. Oddly, the outer atmosphere of Venus is moving very slowly; it is literally wrapped in a violent whirlwind! Venus takes 225 earth days to make one complete revolution around the sun; Earth, of course, completes a longer annual trip in 365 days. A Venus day is longer than its year!
Venus's reputation as a planet of beauty and mystery remained untarnished until the last few decades. The Soviets made several successful Venus probes in the early 1970s. Their earlier attempts had been unexplainable failures; perfectly functioning equipment stopped transmitting long before it reached the Venusian surface. Finally the Soviet scientists arrived at the inescapable conclusion that the probes had been crushed and/or burned in Venus's atmosphere.
Then in 1978, the United States was successful with the Pioneer Venus craft, which has been circling the planet continuously and mapping its surface. Soviet and U.S. probes have found the terrain to be remarkably bare of dust or soil and covered with basaltic rocks that resemble the lava flows on Earth's ocean floors. No doubt these rocks are basaltic flows kept smooth and flat by the immense pressure of the atmosphere, just as oceanic water pressure keeps the marine lava flows flat—faced and spread out.
Scientists now know that Venus is a waterless and hostile world, baking in a hellish heat of about the temperature of molten lead, 900 degrees Fahrenheit. It is oppressed by a thick atmosphere of carbon dioxide and sulfuric acid clouds that bear down on its surface with a pressure 90 times greater than that of Earth. This is equivalent to pressure 3,000 feet below the surface of the oceans. Only about 2 percent of the solar energy penetrates the thick cloud cover and reaches the surface of the planet. Clearly the thermal energy that does reach the surface is trapped by the carbon dioxide atmosphere and the clouds of sulfuric acid. This produces an exaggerated form of greenhouse effect. Continuous for billions of years, the effect has made the surface of Venus into a superfurnace that would easily melt lead.
Recent Venus probes have indicated that the planet's atmosphere is more dynamic and complex than that of Earth. Instruments have recorded frequent lightning discharges with thunder that reverberates for 15 minutes or more! On Earth neither lightning nor thunder lasts more than a few seconds. Its existence on Venus indicates that the range of conditions under which lightning can occur is much greater than previously imagined. The bolts of lightning must be incredibly large, and the frequency suggests that the surface of the planet is never really blacked out but is constantly bathed in a flashing eerie greenish light.
Scientists believe that acid rain falls almost constantly from the thick cloud covering. When it gets close to the planet's surface, however, the intense heat separates the precipitation into its component parts; none of it reaches the surface of the planet. On Earth such a phenomenon, called "ghost rain," occurs in hot deserts such as Death Valley. The rain falls from the clouds in heavy loads, but heat causes it to evaporate before it can reach the desert floor. So it returns to the clouds from which it came. Just as on Venus, scarcely a drop of the rain hits the ground below.
On May 4, 1989, the unmanned spacecraft Magellan was launched from the shuttle Discovery. The Magellan is equipped with an imaging radar system designed to "see" through Venus's cloud cover and obtain detailed photograph—like images of the planet's surface. It reached Venus on August 10, 1990, and began taking the sharpest images of the planet ever seen. This spacecraft was placed in an elliptical orbit, and about 90 percent of the surface of the planet has been radar photographed and mapped to date.
Like a crazed plastic surgeon, plate tectonics continually reshapes the face of the earth, tearing the planetary skin in some places and tucking it away in others. Images of Venus sent back by the Magellan probes suggest that certain elements of plate tectonics have also scarred this nearby planet, even though the mechanism appears somewhat different. The surface of Venus contains the same type of geologic features found on Earth, and they can best be explained by plate tectonics. Deep valleys, huge volcanoes, extensive plateaus, and hills are present on both planets although they differ in size, shape and distribution. A major difference between the two planets is that the surface of Venus is mostly flat, gentle rolling plains.
An outstanding geologic feature reported by radar findings is a canyon on Venus that is larger than Valles Marineres, present on the planet Mars. The latter was previously the largest known canyon in the solar system. Mapped by radar, the Venusian canyon's measurements are 3 miles deep, 175 miles wide, and over 900 miles long.
Scientists now know that Venus is a far cry from the moist, life—giving paradise once envisioned for the planet of love and beauty. In fact, of all the planets in our solar system, Venus is the closest to what Dante must have envisioned for his inferno. Getting right down to it, any astronaut to land on this planet and step out of his or her protective spacecraft would be instantly poisoned, squashed, and fried.