Welcome to brain Stuff production of iHeart Radio, Hey brain Stuff Lauren Boba Bam here after the moon. Venus is the second brightest natural object in the night sky, partially because this planet is covered by reflective clouds that naked eyes and optical telescopes can't penetrate. With the Venusian surface hidden from view, generations of fiction writers used to speculate
like wild about the mysterious terrain beneath those clouds. For example, Tarzan creator Edgar Rice Burrows portrayed Venus as a world with lush forests and arboreal cities in four pulp novel. But then science intervened. The idea that Venus is habitable pretty much imploded during the Cold War. In nine six, radio telescope observations show that the planet had surface temperatures and excess of six hundred and eighteen degrees fahrenheit that's
three degrees celsius. And believe it or not, those readings were kind of low. We now know the average surface temperature on Vena is a blistering eight hundred and sixty four degrees fahrenheit or four hundred and sixty two celsius. It's the hottest planet in our Solar system. Even though mercury is closer to the Sun on the face of Venus, the atmospheric pressure is crushing ly extreme, and lead would melt into a puddle. But as hellish as this place sounds,
it actually has a lot in common with Earth. The two worlds are quite similar in size. If you were to stuff Venus inside our planet a Matroshka doll style, it would occupy roughly eight of Earth's total volume. Venus has Earth beaten in some key regards, though Earth displays a slight midsection bulge, being wider around its equator than it is from one pole to the other. Conversely, Venus
is almost a perfect sphere. What gives well when a massive celestial body like a star or planet spins quickly around its access centrifugal force will give it a more dramatic bulge around its equator. However, Venus has an ultra
slow rotation speed. It takes the equivalent of two hundred and forty three earth days for Venus to complete one full rotation around its axis, and only two d and twenty five earth days to finish a new lap around the Sun. So, in other words, a day on Venus lasts longer than a Venetian year does, and get this from our self centered perspective, Venus spins backward. Most of the planets in the Solar System rotate from west to east.
Irnus and Venus buck that trend. On those two worlds, the sun appears to rise in the west and set in the east. Nobody knows how that came to pass. Astronomers think Venus used to move in a counterclockwise direction like Earth, but at some point its spin might have reversed. Alternatively, perhaps the Sun's gravitational influence or a collision with a large object caused the entire planet to flip upside down.
In December of nineteen two, Venus became the first planet to get a fly by visit from a man made spacecraft. Exploiting a brief window of opportunity, NASA's Mariner two probes to need this world up close from distances as near as twenty one miles that's about thirty four thousand kilometers. The onboard instruments taught us a great deal. Mariner, too, confirmed that Venus does not have an Earth like magnetic field, and it recorded surface temperatures within the expected range. A
young Carl Sagan helped design the Mariner to probe. He unsuccessfully lobbied to have the spacecraft fitted with a camera because close up pictures of Venus might quote answer questions that we were too dumb to even pose. By the time Mariner Too launched, scientists already knew that there were high levels of carbon dioxide in the Venusian atmosphere, and that composition should give us pause. Carbon dioxide makes up a whopping of Venus's atmosphere. Scientists attribute this to a
runaway greenhouse effect. Theoretically, the planet used to have a more temperate climate that could have remained stable for billions of years. Back then, oceans of liquid water may have covered its surface, though we don't know for sure. Things changed as our growing sun became hotter. Any oceans would have evaporated during this time, and astronomers think much of the carbon dioxide in Venusian rocks leached out and traveled skyward.
While the atmosphere changed, it got better at trapping heat, creating a vicious cycle that worsened the problem. Inevitably, temperatures spiked and stayed. Since our own planet has a major greenhouse gas problem, Venus could offer us some important insights regarding climate change, but sending probes to explore it has always presented major challenges. On Venus, the surface gravity is
comparable to what you and I experience on Earth. What's not comparable is that atmospheric pressure, which is nine two times greater on the face of Venus than it is here. Faced with extreme temperatures and high pressure, it's no wonder that man made objects don't last long in the planet's environment. When the Soviet Venera thirteen probe landed on Venus two, it stayed intact for a record setting one and twenty seven minutes before it was destroyed. Mind you, this wasn't
the U s s RS first rodeo. Previous Venera spacecrafts had successfully visited the planet's atmosphere and touched down on its outer crust brief though their visits were these probes captured the first ever photographs of the Venusian surface. NASA's Magellan spacecraft provided further insights as it mapped of the planet's face. All in all, Venus boasts more than sixteen thousand volcanoes and volcanic features, but we don't know if
any of these are still active. Highland plateaus, deep canyons, and meteorite impact craters have also been discovered there. Although Venus is about four point six billion years old, its crust is thought to be much younger, with an estimated age of just three to six hundred million years. Venus
lacks tectonic plates as we know them on Earth. Nonetheless, some geologists think that upwellings of magma occasionally recycle sections of the crust, long before it was an object of scientific study, or of Edgar Rice Burrough's novel, Venus mesmerized our ancestors, Bright and beautiful. The cloud adorned planet derives its name from the Roman goddess of love. Ancient mathematicians mapped its progress across the sky, and Galileo took detailed
notes about its moonlike phases. Somehow, knowing that Venus is a stifling hothouse doesn't diminish its alure. With every new discovery inspires curiosity and awe. Today's episode was written by Mark Mancini and produced by Tyler Clang. Brain Stuff is
a production of I Heart Radio's How Stuff Works. For more in this and lots of other hot topics, visit our home planet, How stuff works dot com and for more podcast my Heart Radio, visit the iHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.