WEBVTT - BrainStuff Classics: How Does Venus Work?

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<v Speaker 1>Welcome to BrainStuff, a production of iHeart Podcasts. Hey BrainStuff,

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<v Speaker 1>Lauren Vogelbaum here with a classic episode of the show

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<v Speaker 1>for you. In this one, we take a peek at Venus,

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<v Speaker 1>a planet that's nearly a twin to Earth in size

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<v Speaker 1>and basic composition, but with some serious differences in surface conditions.

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<v Speaker 2>Hey BrainStuff, Lauren Vogelbaum here. After the moon, Venus is

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<v Speaker 2>the second brightest natural object in the night sky, partially

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<v Speaker 2>because this planet is covered by reflective clouds that naked

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<v Speaker 2>eyes and optical telescopes can't penetrate. With the Venusian surface

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<v Speaker 2>hidden from view, generations of fiction writers used to speculate

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<v Speaker 2>like wild about the mysterious terrain beneath those clouds. For example,

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<v Speaker 2>Tarzan creator Edgar Rice Burroughs portrayed Venus as a world

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<v Speaker 2>with lush forests and arboreal cities in a 1934 pulp novel.

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<v Speaker 2>But then science intervened. The idea that Venus is habitable

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<v Speaker 2>pretty much imploded during the Cold War. In 1956, radio

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<v Speaker 2>telescope observations showed that the planet had surface temperatures in

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<v Speaker 2>excess of 618 degrees Fahrenheit. That's 326 degrees Celsius. And

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<v Speaker 2>believe it or not, Those readings were kind of low.

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<v Speaker 2>We now know the average surface temperature on Venus is

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<v Speaker 2>a blistering 864 degrees Fahrenheit, or 462 Celsius. It's the

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<v Speaker 2>hottest planet in our solar system, even though Mercury is

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<v Speaker 2>closer to the Sun. On the face of Venus, the

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<v Speaker 2>atmospheric pressure is crushingly extreme, and lead would melt into

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<v Speaker 2>a puddle. But as hellish as this place sounds, it

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<v Speaker 2>actually has a lot in common with Earth. The two

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<v Speaker 2>worlds are quite similar in size. If you were to

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<v Speaker 2>stuff Venus inside our planet, a Matryoshka doll style, it

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<v Speaker 2>would occupy roughly 86% of Earth's total volume. Venus has

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<v Speaker 2>Earth beaten in some key regards, though. Earth displays a

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<v Speaker 2>slight midsection bulge, being wider around its equator than it

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<v Speaker 2>is from one pole to the other. Conversely, Venus is

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<v Speaker 2>almost a perfect sphere. What gives? Well, when a massive

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<v Speaker 2>celestial body like a star or planet spins quickly around

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<v Speaker 2>its axis, centrifugal force will give it a more dramatic

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<v Speaker 2>bulge around its equator. However, Venus has an ultra-slow rotation speed.

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<v Speaker 2>It takes the equivalent of 243 Earth days for Venus

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<v Speaker 2>to complete one full rotation around its axis, and only

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<v Speaker 2>225 Earth days to finish a new lap around the Sun. So,

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<v Speaker 2>in other words, a day on Venus lasts longer than

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<v Speaker 2>a Venetian year does. And get this, from our self-centered perspective,

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<v Speaker 2>Venus spins backward. Most of the planets in the solar

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<v Speaker 2>system rotate from west to east. Uranus and Venus buck

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<v Speaker 2>that trend. On those two worlds, the sun appears to

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<v Speaker 2>rise in the west and set in the east. Nobody

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<v Speaker 2>knows how that came to pass. Astronomers think Venus used

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<v Speaker 2>to move in a counterclockwise direction like Earth, but at

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<v Speaker 2>some point, its spin might have reversed. Alternatively, perhaps the

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<v Speaker 2>sun's gravitational influence or a collision with a large object

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<v Speaker 2>caused the entire planet to flip upside down. In December

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<v Speaker 2>of 1962, Venus became the first planet to get a

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<v Speaker 2>flyby visit from a man-made spacecraft. Exploiting a brief window

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<v Speaker 2>of opportunity, NASA's Mariner 2 probe studied this world up close,

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<v Speaker 2>from distances as near as 21,000 miles, that's about 34,000 kilometers.

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<v Speaker 2>The onboard instruments taught us a great deal. Mariner 2

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<v Speaker 2>confirmed that Venus does not have an Earth-like magnetic field,

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<v Speaker 2>and it recorded surface temperatures within the expected range. A

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<v Speaker 2>young Carl Sagan helped design the Mariner 2 probe. He

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<v Speaker 2>unsuccessfully lobbied to have the spacecraft fitted with a camera

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<v Speaker 2>because close-up pictures of Venus might, quote, answer questions that

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<v Speaker 2>we were too dumb to even pose. By the time

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<v Speaker 2>Mariner 2 launched, scientists already knew that there were high

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<v Speaker 2>levels of carbon dioxide in the Venusian atmosphere, and that

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<v Speaker 2>composition should give us pause. Carbon dioxide makes up a

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<v Speaker 2>whopping 96% of Venus's atmosphere. Scientists attribute this to a

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<v Speaker 2>runaway greenhouse effect. Theoretically, the planet used to have a

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<v Speaker 2>more temperate climate that could have remained stable for billions

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<v Speaker 2>of years. Back then, oceans of liquid water may have

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<v Speaker 2>covered its surface, though we don't know for sure. Things

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<v Speaker 2>changed as our growing sun became hotter. Any oceans would

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<v Speaker 2>have evaporated during this time. And astronomers think much of

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<v Speaker 2>the carbon dioxide in Venusian rocks leached out and traveled skyward.

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<v Speaker 2>While the atmosphere changed, it got better at trapping heat,

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<v Speaker 2>creating a vicious cycle that worsened the problem. Inevitably, temperatures

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<v Speaker 2>spiked and stayed. Since our own planet has a major

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<v Speaker 2>greenhouse gas problem, Venus could offer us some important insights

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<v Speaker 2>regarding climate change. But sending probes to explore it has

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<v Speaker 2>always presented major challenges. On Venus, the surface gravity is

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<v Speaker 2>comparable to what you and I experience on Earth. What's

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<v Speaker 2>not comparable is that atmospheric pressure, which is 92 times

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<v Speaker 2>greater on the face of Venus than it is here.

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<v Speaker 2>Faced with extreme temperatures and high pressure, it's no wonder

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<v Speaker 2>that man-made objects don't last long in the planet's environment.

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<v Speaker 2>When the Soviet Venera 13 probe landed on Venus in 1982,

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<v Speaker 2>it stayed intact for a record-setting 127 minutes before it

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<v Speaker 2>was destroyed. Mind you, this wasn't the USSR's first rodeo.

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<v Speaker 2>Previous Venera spacecrafts had successfully visited the planet's atmosphere and

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<v Speaker 2>touched down on its outer crust. Brief though their visits were,

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<v Speaker 2>these probes captured the first-ever photographs of the Venusian surface.

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<v Speaker 2>NASA's Magellan spacecraft provided further insights, as it mapped 98%

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<v Speaker 2>of the planet's face. All in all, Venus boasts more

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<v Speaker 2>than 16,000 volcanoes and volcanic features, but we don't know

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<v Speaker 2>if any of these are still active. Highland plateaus, deep canyons,

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<v Speaker 2>and meteorite impact craters have also been discovered there. Although

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<v Speaker 2>Venus is about 4.6 billion years old, its crust is

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<v Speaker 2>thought to be much younger, with an estimated age of

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<v Speaker 2>just 300 to.

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<v Speaker 1>600 million years.

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<v Speaker 2>Venus lacks tectonic plates as we know them on Earth. Nonetheless,

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<v Speaker 2>some geologists think that upwellings of magma occasionally recycle sections

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<v Speaker 2>of the crust. Long before it was an object of

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<v Speaker 2>scientific study, or of Edgar Rice Burroughs' novels, Venus.

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<v Speaker 1>Mesmerized our ancestors.

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<v Speaker 2>Bright and beautiful, the clouded orange planet derives its name

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<v Speaker 2>from the Roman goddess of love. Ancient mathematicians mapped its

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<v Speaker 2>progress across the sky, and Galileo took detailed notes about

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<v Speaker 2>its moon-like phases. Somehow, knowing that Venus is a stifling

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<v Speaker 2>hothouse doesn't diminish its allure. With every new discovery, it

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<v Speaker 2>inspires curiosity and awe. Today's episode is based on the

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<v Speaker 2>article Venus, Earth's Blazing Hot and Bizarre Twin on HowStuffWorks.com,

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<v Speaker 2>written by Mark Mancini. BrainStuff is a production of iHeart

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<v Speaker 2>Podcasts in partnership with HowStuffWorks.com and is produced by Tyler Klang.

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<v Speaker 2>For more shows from iHeart Podcasts, visit the iHeart Radio app,

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<v Speaker 2>Apple Podcasts, or wherever you listen to your favorite shows.