Mohawk Valley Astronomical Society

Return to Newsletter Index

The Glows of Venus

by Perry Pezzolanella, MVAS

Early in the morning or late in the evening you will often see a silvery star shining brighter than any other star in the twilight sky. It is hard to believe that beneath that soothing, silvery shine is an environment so hostile that it frightens the imagination. When you consider the climate on Venus, you gain a deeper appreciation of Earth.

Venus is the second planet from the Sun and almost as large as Earth, but the similarity ends there. Let us take a journey to the planet called the goddess of love. In our imagination no physical harm can befall us, but we will still be acutely aware of the dangers of an intensely hostile planet. As we arrive at Venus, we see a world completely covered with clouds and no hint of the surface below. The clouds have a strange yellow tint and we ponder why. We pass over into the night side of Venus and see the mysterious Ashen Light deep within the clouds. This is a faint, mysterious glow that is sometimes seen from Earth. We still cannot figure out the source, even this close, but it seems to come from beneath the clouds. We also see an occasional flash of lightning. As we cross into the morning side of Venus, we take our plunge into the clouds and soon discover why they are yellow. These clouds are made of concentrated sulfuric acid instead of water! Here at the cloud tops it is a frigid -40° F and the winds howl at 200 miles per hour in the thin carbon dioxide atmosphere. We run into severe turbulence deeper down as we hit a squall. Sulfuric acid rain lashes us as lightning flashes angrily and the thunder booms endlessly. We are 35 miles above the surface and a balmy 65° F with the air pressure similar to Earth’s. This is as good as it gets if we ignore the acid rain and sizzling lightning. We break out of the clouds at 30 miles above the surface, but it is still obscured from the sulfuric acid mist. Looking down there is nothing but a reddish- orange glow from the tremendous heat and pressure. It is now 200° F with winds gusting to 100 miles per hour and an atmosphere five times thicker than Earth’s and it only gets worse. The horror really begins as we decide to go into a free-fall through what feels like fiery oil.

As we fall below the haze we begin to see the scorched landscape below that has been shaped and sculpted by massive volcanic eruptions and lava flows. Far off on the horizon we see a volcano erupting and the ash cloud is laced with lightning; perhaps this is what we flew over a few minutes ago! The light around us is like a cloudy winter’s day on Earth with a deep orange glow. As we get within 12 miles of the surface we become fully aware of the inferno that awaits us as the temperature has soared to 600 °F and the air pressure is 21 times Earth’s, but the wind has slowed to 30 miles per hour. We finally land with a thud and wonder if we actually descended into Hades by mistake. The temperature is 900 °F with an air pressure 90 times Earth’s! The wind is only 3 miles per hour, but in this dense atmosphere it feels like a fiery current that is capable of splitting the rocks around us. The air is a pressurized mixture of carbon dioxide and sulfuric acid giving everything an eerie orange hue, much like a sunset on Earth. The sun is twice as large as seen from Earth and tries to break out of the rapidly changing cloud decks overhead. Lightning occasionally flickers with loud rumbles of thunder. The rocks beneath our feet are half way to their melting points, but because Venus is so dry, they do not collapse into a mass of putty.

A day on Venus lasts a long time, about 117 Earth days. Daylight and nighttime each last about 59 days. The Sun rises in the west and sets in the east because Venus rotates backwards. Watching the sun set on Venus would be enchanting or maybe frightening or perhaps both. As the bright glow of the Sun sinks lower in the east, the scenery, already bathed in an orange glow, begins to take on an increasingly redder glow. As the light level drops during the course of the two-week long twilight, we begin to notice that the rocks appear to be glowing dull red much like hot coal. Soon we realize that it will not be such a dark night after all. Infrared images from the Galileo spacecraft (while on its way to Jupiter) of the night side of Venus vividly revealed the hotter lowlands shining brightly through the thinner patches of clouds. Perhaps this is the source of the Ashen Light? As night finally falls we see patches and streaks of red glowing rocks as far as the eyes can see, only interrupted by an occasional flash of lightning high above. In this inferno, lead, zinc, and tin would melt and water would vaporize in seconds! Organic compounds such as those that sustain life would instantly disintegrate.

The night brings no relief from the heat and neither would a trip to the poles. The best place to cool off would be in the mountains. The temperature drops roughly 5 degrees for every 1000-foot increase of elevation. So the highest mountain, Maxwell Montes at 37,000 feet, would be a chilly 720 °F and a great place to escape the glowing rocks! What a sight to behold, looking down over the vast, hot lowlands glowing red. Even more fascinating would be Diana Chasma, nearly 2 miles deep and hundreds of miles long, four times the length of the Grand Canyon, glowing faintly in the night. The bottom of this and many of the other deep canyons on Venus may exceed 1000° F! As if all of this is not enough, besides the possible glow of flowing lava, there may be active fumaroles, or volcanic vents dotting the surface. These may make the immediate surroundings as hot as 1300° F!

There might be a special time during twilight that would give the perfect balance of glow between the deepening of the red sky and the increasing glow of the hot rocks. That moment could be savored by simply walking into the sunset. Since Venus rotates so slowly, the relative speed of the ground near the equator is about 8 miles per hour and even slower towards the poles. An easy walking pace could forever keep one in an eternal twilight if they were physically up to the challenge. Perhaps the poles are the best place for that perfect infernal glow. Venus is only tilted three degrees on its axis, so the Sun would always be near the horizon regardless of the time of its year. So perhaps there would be some choice real estate where one could live and continuously enjoy a deep red twilight sky perfectly balanced against a panorama of faintly red glowing rocks strewn across the countryside. Maybe Venus is not such a bad place after all?