7 Eye-Opening Facts About Venus

For all the efforts to find another inhabitable planet orbiting a distant star, it might surprise you to learn that a very real Earth 2.0 exists in this solar system—just one planet over. Not Mars (which actually isn't much like Earth at all), but rather, our other neighbor: Venus. Mental Floss spoke to geophysicist Bob Grimm, a program director at the Southwest Research Institute and chair of NASA's Venus Exploration Analysis Group. Here are a few things we learned about Earth's twin sister.

1. BY THE NUMBERS, VENUS LOOKS A LOT LIKE EARTH.

Venus has a radius of 3760 miles. Earth's is 3963. Its mass and gravity are 82 percent and 91 percent of Earth's, respectively—pretty similar as planets go. Venus is composed of a mostly basalt crust, silicate mantle, and iron core. Earth is the same. The two planets likely share common origins somewhere around 4.5 billion years ago.

In fact, by all accounts, we should be able to land our flying saucers on Venus, saddle up a dinosaur, and start building tract housing. It's perfect for colonization, but for a few minor differences. Its year is shorter, at 224.7 days. (And its days are much longer, at 243 Earth days per Venus day.) The Sun would rise in the west and set in the east because of the planet's retrograde orbit (which, by the way, is the most circular of any planet in the solar system). And then there's another small problem …

2. IT'S HOT. VERY, VERY HOT.

Venus is hotter than Mercury, despite being 30 million miles farther from the Sun. How hot? Hot enough, on average, to melt a block of lead the way a block of ice would melt on Earth. Venus suffers from a runaway greenhouse effect. Sunlight penetrates the dense clouds surrounding Venus, heating the landscape. The ground in turn blasts out heat, which rises and tries to escape the atmosphere. But carbon dioxide, which makes up 96 percent of its atmosphere, traps the heat, keeping things nice and toasty, around 900°F. And those clouds aren't the white, fluffy variety. They're made of droplets of sulfuric acid, which makes its lightning storms especially harrowing.

3. VENUS HOLDS THE KEY TO UNDERSTANDING EXOPLANETS.

"'Does Earth-size mean Earth-like?' is a basic problem of planetology," says Grimm. "Understanding how Earth and Venus diverged is essential to understanding comparative planetology, and potentially exoplanets—these worlds orbiting distant stars that are being discovered telescopically."

Knowing more about Venus would help scientists better distinguish potentially habitable worlds out there, and better understand how a good world can go bad, from a sustaining-life perspective. "Geology and meteorology are intimately related to the evolution of the Earth and the evolution of life on Earth," Grimm notes. "Even though we may not be looking for life on Venus, it's important to understanding Earth's place in the solar system and in the universe."

4. IT DIDN'T HAVE DINOSAURS. (PROBABLY.)

You might have run across old illustrations of Venus with conditions similar to the Carboniferous Period on Earth. Astronomers have known for just under a hundred years that Venus's atmosphere is devoid of oxygen, without which you can't have water. But even a modest backyard telescope can see the clouds enveloping our neighbor, and as Carl Sagan explained, from there you're only a couple of erroneous jumps from assuming a brontosaurus. (Thick clouds mean more water than land. More water than land means swamps. Dinosaurs lived in swamps. Dinosaurs live on Venus. QED.) Said Sagan: "Observation: There was absolutely nothing to see on Venus. Conclusion: It must be covered with life."

But seeing is believing, and the Mariner and Venera series of probes disabused us of the romantic notion of a swampy neighbor to the left. Still, we should probably send robots there to check. Just to be sure.

5. WE HAVEN'T BEEN TO ITS SURFACE SINCE THE 1980S.

Venus was the first planet we visited, with Mariner 2 achieving the first successful planetary encounter in 1962. Four years later, Venera 3 on Venus became the first spacecraft to touch the surface of another planet. (Communications were lost long before impact, but unless a dinosaur ate it, the spacecraft probably touched the ground.) Our first graceful landing on another planet? Venera 7 on Venus. Our efforts to reach its surface go back much further than that, though. The transit of Venus in 1761 practically invented the notion of an international science community. But we abandoned the surface of Venus in 1984, and NASA hasn't launched an orbiter to Venus since Magellan in 1989. 

Since then, the Venus-science community has been trying to get another mission to the launch pad. Presently, U.S. planetary scientists have submitted proposals to NASA for a sub-$1 billion New Frontiers–class mission. They are also working with their colleagues in Russia to launch a joint mission called Venera-D. "We need better radar views of the surface," says Grimm, "and that has to happen at some point to understand the geology. We need deep probes into the atmosphere to understand it better, and we need a new generation of landers."

6. A NEW MISSION COULD HELP SOLVE OUR BIGGEST QUESTIONS.

"There is evidence in the deuterium-to-hydrogen ratio that Venus once had water, maybe hundreds of meters deep, more like a global sea than an ocean," says Grimm. A theoretical paper published last year posed a climate model for Venus suggesting that water could have existed on its surface as recently as 1 billion years ago. Clouds could form in a certain way, shielding the surface from the Sun and allowing stable water at the surface. Furthermore, near-infrared observations support the argument for a watery Venusian past. ESA's Venus Express orbiter in 2012 found evidence of granite-like rocks on some parts of the planet. Granite requires a multiple melting process in the presence of water. A mission to Venus could confirm this.

Meanwhile, one of the most significant revelations from Magellan is that there are only around 1000 craters on the surface with no differences in density, and it is hard to find craters that are obviously in a state of being wiped out by lava, or being faulted. Venus does not have plate tectonics, one of the central mechanisms that organizes all geology on the Earth. So what happened to the surface of Venus? Where is the evidence of the Late Heavy Bombardment seen on other terrestrial planets and moons? One hypothesis is that all of Venus was resurfaced at once. There may have been a global catastrophe on Venus, perhaps as recently 750 million years ago, that quickly "reset" its surface. Other models suggest a subtler resurfacing at work in which craters might be erased over billions of years.

"So this whole idea of the surface age of Venus is a pivotal question for how planets evolve geologically," says Grimm. "But what was Venus like before that? Was there a single catastrophe, or have there been many? Was there just one catastrophe and Venus was watery before that, or has Venus operated in a steady state going back to the first billion years? There is more consensus that in the first several hundred million years to billion years, there could have been water." Further landings on Venus could help us solve the mystery of when Venus's surface was formed, if there was ever water there, and why, if it existed, it went away.

7. VENUS IS KIND OF A YELLOW, EXTREME VERSION OF HAWAII.

If Matt Damon were to get stranded on Venus in a sequel to The Martian, he would need to be resourceful indeed to survive the heat and the corrosive air. But what he would find wouldn't be wholly alien. The winds at the surface of Venus are very gentle, around a meter or so per second. The vistas would consist of hills and ridges, with dark lava rocks of various types, mostly basalt. The atmospheric pressure is 90 times greater than Earth at sea level, so walking there would feel a lot like swimming here.

"I don't think [Venus] would look wavy and hot-hazy, because the atmosphere is pretty stable and uniform right at the surface," says Grimm. "It would be harder to walk through the dense atmosphere, but not as hard as walking through water. We know from landings that it's kind of yellow because of the sulfur in the atmosphere. So with the abundance of lavas in many places on Venus, it sort of looks like a yellowish Hawaii."

The Science Behind Why the Earth Isn't Flat

Earth as captured from near the lunar horizon by the Lunar Reconnaissance Orbiter in 2015.
Earth as captured from near the lunar horizon by the Lunar Reconnaissance Orbiter in 2015.
NASA

On March 24, 2018, flat-earther Mike Hughes set out prove that the Earth is shaped like a Frisbee. The plan: Strap himself to a homemade steam-powered rocket and launch 52 miles into sky above California’s Mojave Desert, where he'd see Earth's shape with his own eyes.

It didn't matter that astronauts like John Glenn and Neil Armstrong had been to space and verified that the Earth is round; Hughes didn't believe them. According to The Washington Post, Hughes thought they were "merely paid actors performing in front of a computer-generated image of a round globe."

The attempt, ultimately, was a flop. He fell back to Earth with minor injuries after reaching 1875 feet—not even as high as the tip of One World Trade Center. For the cost of his rocket stunt ($20,000), Hughes could have easily flown around the world on a commercial airliner at 35,000 feet.

Hughes isn't alone in his misguided belief: Remarkably, thousands of years after the ancient Greeks proved our planet is a sphere, the flat-Earth movement seems to be gaining momentum. "Theories" abound on YouTube, and the flat-Earth Facebook page has some 194,000 followers.

Of course, the Earth isn't flat. It's a sphere. There is zero doubt about this fact in the real, round world. To say the evidence is overwhelming is an understatement.

HOT SPINNING BODIES

Not every celestial body is a sphere, but round objects are common in the universe: In addition to Earth and all other known large planets, stars and bigger moons are also ball-shaped. These objects, and billions of others, have the same shape because of gravity, which pulls everything toward everything else. All of that pulling makes an object as compact as it can be, and nothing is more compact than a sphere. Say, for example, you have a sphere of modeling clay that is exactly 10 inches in diameter. No part of the mass is more than 5 inches from the center. That's not the case with any other shape—some part of the material will be more than 5 inches from the center of the mass. A sphere is the smallest option.

Today the Earth is mostly solid with a liquid outer core, but when the planet was forming, some 4.5 billion years ago, it was very hot and behaved like more like a fluid—and was subject to the squishing effects of gravity.

And yet, the Earth isn't a perfect sphere; it bulges slightly at the equator. "Over a long time-scale, the Earth acts like a highly viscous fluid," says Surendra Adhikari, a geophysicist at the Jet Propulsion Laboratory in Pasadena, California. The Earth has been spinning since it was formed, and "if you have a spinning fluid, it will bulge out due to centrifugal forces." You can see evidence for this at the equator, where the Earth's diameter is 7926 miles—27 miles larger than at the poles (7899 miles). The difference is tiny—just one-third of 1 percent.

THE SHADOW KNOWS

The ancient Greeks figured out that Earth was a sphere 2300 years ago by observing the planet's curved shadow during a lunar eclipse, when the Earth passes between the Sun and the Moon. Some flat-Earth believers claim the world is shaped like a disk, perhaps with a wall of ice along the outer rim. (Why no one has ever seen this supposed wall, let alone crashed into it, remains unexplained.) Wouldn't a disk-shaped Earth also cast a round shadow? Well, it would depend on the orientation of the disk. If sunlight just happened to hit the disk face-on, it would have a round shadow. But if light hit the disk edge-on, the shadow would be a thin, straight line. And if the light fell at an oblique angle, the shadow would be a football–shaped ellipse. We know the Earth is spinning, so it can't present one side toward the Sun time after time. What we observe during lunar eclipses is that the planet's shadow is always round, so its shape has to be spherical.

The ancient Greeks also knew Earth's size, which they determined using the Earth's shape. In the 2nd century BCE, a thinker named Eratosthenes read that on a certain day, the people of Syene, in southern Egypt, reported seeing the Sun directly overhead at noon. But in Alexandria, in northern Egypt, on that same day at the same time, Eratosthenes had observed the Sun being several degrees away from overhead. If the Earth were flat, that would be impossible: The Sun would have to be the same height in the sky for observers everywhere, at each moment in time. By measuring the size of this angle, and knowing the distance between the two cities, Eratosthenes was able to calculate the Earth's diameter, coming up with a value within about 15 percent of the modern figure.

And when Columbus set sail from Spain in 1492, the question wasn't "Would he fall off the edge of the world?"—educated people knew the Earth was round—but rather, how long a westward voyage from Europe to Asia would take, and whether any new continents might be found along the way. During the Age of Exploration, European sailors noticed that, as they sailed south, "new" constellations came into view—stars that could never be seen from their home latitudes. If the world were flat, the same constellations would be visible from everywhere on the Earth's surface.

Finally, in 1522, Ferdinand Magellan's crew became the first people to circle the globe. Like Columbus, Magellan also set off from Spain, in 1519, heading west—and kept generally going west for the next three years. The expedition wound up back at the starting point (though without Magellan, who was killed during a battle in the Philippines). And speaking of ships and seafaring: One only needs to watch a tall ship sailing away from port to see that its hull disappears before the top of its mast. That happens because the ship is traveling along a curved surface; if the Earth were flat, the ship would just appear smaller and smaller, without any part of it slipping below the horizon.

THE EVIDENCE IS ALL AROUND (AND ALL ROUND)

But you don't need a ship to verify the Earth's shape. When the Sun is rising in, say, Moscow, it's setting in Los Angeles; when it's the middle of the night in New Delhi, the Sun is shining high in the sky in Chicago. These differences occur because the globe is constantly spinning, completing one revolution per day. If the Earth were flat, it would be daytime everywhere at once, followed by nighttime everywhere at once.

You also experience the Earth's roundness every time you take a long-distance flight. Jetliners fly along the shortest path between any two cities. "We use flight paths that are calculated on the basis of the Earth being round," Adhikari says. Imagine a flight from New York to Sydney: It would typically head northwest, toward Alaska, then southwest toward Australia. On the map provided in your airline's in-flight magazine, that might look like a peculiar path. But wrap a piece of string around a globe, and you'll see that it’s the shortest possible route.

"If the Earth were flat," Adhikari says, "the trajectory would be completely different." How different depends on which way the globe is sliced into a flattened map, but if it looked like it does on a Mercator-projection map, it might head east and pass over Africa.

Engineers and architects also take the Earth's curvature into account when building large structures. A good example is the towers that support long suspension bridges such as the Verrazano Narrows bridge in New York City. Its towers are slightly out of parallel with each other, the tops being more than 1.5 inches further apart than their bases. If the Earth were flat, the bottom of the towers would be separated by the exact same distance as the top of the towers; the planet's curvature forces the tops of the towers apart.

And for the last half-century, we've had eyewitness and photographic proof of the Earth's shape. In December 1968, the crew of Apollo 8 left Earth for the Moon. When they looked out of the Command Module windows, they saw a blue-and-white marble suspended against the blackness of space. On Christmas Eve, lunar module pilot William Anders snapped the famous "Earthrise" photograph. It gave us an awe-inspiring perspective of our round planet that was unprecedented in human history—but it wasn't a surprise to anyone.

What Happens When an Astronaut Gets Sick in Space?

NASA/Getty Images
NASA/Getty Images

Astronauts are among the fittest and healthiest people in the world. They're rigorously trained, vetted, and quarantined before they’re allowed up in space—and yet, despite all those precautions, they do sometimes get sick. Apollo 13's Fred Haise, for example, had to deal with a painful kidney infection during the dangerous mission that gave us the phrase "Houston, we have a problem," and one-time astronaut Jake Garn, a Utah senator, got so motion-sick during a 1985 Discovery mission that astronauts now rate their nausea levels on the Garn Scale. And because space missions are on a strict schedule planned far in advance, sick astronauts on a space mission can't just pop down to Earth to see a doctor.

But when astronauts fall ill, they don't have to worry—NASA and other space agencies that have missions aboard the ISS are prepared.

SPACE ADAPTATION SICKNESS

Zero gravity can change a lot of normal bodily functions. One effect it has is to make the fluids inside the body float, which confuses the inner ears and makes them unable to tell up from down. This causes space adaptation syndrome (SAS), a common illness that's kind of like seasickness in space. Motion sickness, the most frequently reported ailment, is a subset of SAS; it affects 67 to 75 percent of astronauts.

It takes a few days for astronauts' bodies to adjust to weightlessness, during which they may experience symptoms ranging from headaches to vomiting. And though it might seem like a nightmare to deal with puke, NASA has a system: Astronauts carry special barf bags with attached face wipes and Ziploc seals that they can use during launch or while in orbit if they get the urge to hurl. Once used, the bags are tossed in the trash.

COLDS AND SNIFFLES

Because astronauts are quarantined before spaceflight, the likelihood of being exposed to a pathogen in space is rare. But if an astronaut does come down with the sniffles, they can expect an Earth cold on steroids: Sinuses don't drain in zero gravity, so congested astronauts feel even stuffier than we do here on the ground. To make matters worse, germs seem to thrive in weightless environments—pathogens can develop “thicker cell walls, greater resistance to antimicrobial agents and a greater ability to form so-called biofilms that cling to surfaces” in zero gravity, according to TIME.

Luckily, colds and even the flu tend to go away on their own, even in space—so astronauts just need to wait it out.

BUMPS, BRUISES, AND OTHER MINOR INJURIES

Astronauts floating around in zero gravity have a tendency to bump into things, which can sometimes cause an injury. When they want to check on a wound, abrasion, or another condition, they place a phone call to a physician on the ground, who will advise them what to do.

“We get calls for bumps, and bruises, and little lacerations or cuts,” Shannan Moynihan, deputy chief of space and occupational medicine at the NASA Johnson Space Center, said at a health tech conference in March 2018. “A typical scenario might be a newbie, somebody who just got up there, trying to Superman through a hatch and not quite making it. So we get a call for a little bump on the forehead and we help them figure out how to take care of that.”

A doctor on Earth can walk an astronaut through how to use and read a modified ultrasound machine on the ISS, for example, or give them additional training in response to a specific medical condition occurring on board. That happened with spaceflight-associated neuro-ocular syndrome, a condition in which ISS astronauts developed visual and structural changes in their eyes during space missions. They were subsequently trained to conduct a series of eye tests on themselves.

FROM EVACUATION TO SURGERY

If there’s anything too serious to deal with on board, astronauts can get back to Earth via the the Soyuz spacecraft that brought them to space—there’s always one docked at the ISS in case of emergency. Medical evacuation has only happened once, in 1986, when a Soviet astronaut named Vladimir Vasyutin had to leave the Salyut-7 Orbital Lab [PDF] because of a prostate infection. His trip back to Earth took about six hours; these days, astronauts can land in less than three and a half.

In the case of a true medical emergency—one that requires surgery—evacuation to Earth is currently the only way for astronauts to get treatment. Surgery in zero gravity isn't yet possible; blood would float straight out of a wound and contaminate the whole cabin. As deep space travel gets more feasible, however, it’s possible that one day a space O.R. might be necessary, and technology is being developed to make potential surgeries easier and cleaner. Scientists are testing a device called the aqueous immersion surgical system (AISS), a saline filled dome that, when placed over a wound, could keep blood and bodily fluids in place.

As humanity pushes further into deep space, medical technology will need to become even more sophisticated. When it comes to deep space missions, NASA representative Stephanie Schierholz tells Mental Floss, “NASA is specifically looking at five hazards of human space travel: space radiation, isolation and confinement, distance from Earth, gravity fields (or lack thereof), and hostile/closed environments that pose the greatest risks to the human mind and body in space.”

Currently, NASA is working on several research and development projects to address the hazards posed by deep space travel, including no-drill dentistry and emergency wound closure, which would need to be usable by astronauts with no formal medical or dental training. And because not all potential illness is physical, Mars settlement simulation projects are helping researchers understand what the psychological, emotional, and social effects of long-term isolation might be on astronauts.

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