The desert planet in ‘Dune’ is plausible, according to science

But giant sandworms are (thankfully) improbable

From a cloud of sand, three giant worms emerge. Their circular mouths are open displaying rows of long teeth that curve into their throats. At least two dozen people dressed in dark full-body suits flee toward the camera across an open expanse of sand from the giant worms. The people seem nearly as small as insects in comparison with the huge worms.

Arrakis, the fictional planet in Dune, would be inhospitable but livable for humans, researchers say. But the giant sandworms depicted in the movies (as in a scene from Dune: Part Two depicted here) and books are implausible.

Courtesy Warner Bros. Pictures

Frank Herbert’s science fiction novel Dune has been praised for its worldbuilding. Herbert created complex societies, religions and economic systems all with rich histories.

Most famous of Herbert’s worlds is the desert planet Arrakis, nicknamed Dune, with its harsh climate and giant sandworms. The planet is the setting for most of the novel and movies based on the book. The second installment of the latest imagining from director Denis Villeneuve, Dune: Part Two, opens in theaters March 1.

Not only did Herbert create a rich fantasy world, he also built a plausible planet, says Alexander Farnsworth, a climate modeler at the University of Bristol in England.

A few years ago, Farnsworth and colleagues made a computer simulation of the climate on Arrakis. People could live on the desert planet, the team concluded, but Herbert probably should have relocated his cities closer to the equator than the poles.

As for the giant sandworms that can swallow mining equipment whole, they push the boundaries of what biology might achieve, says vertebrate paleontologist Patrick Lewis, of Sam Houston State University in Huntsville, Texas.

Science News asked the experts what life on Arrakis might really be like and whether humans living on the planet would need to worry about being eaten by a giant worm.

Building Arrakis

For their Arrakis climate simulation, which you can explore at the website Climate Archive, Farnsworth and colleagues started with the well-known physics that drive weather and climate on Earth. Using our planet as a starting point makes sense, Farnsworth says, partly because Herbert drew inspiration for Arrakis from “some sort of semi-science of looking at dune systems on the Earth itself.”

The team then added nuggets of information about the planet from details in Herbert’s novels and in the Dune Encyclopedia. According to that intel, the fictional planet’s atmosphere is similar to Earth’s with a couple of notable differences. Arrakis has less carbon dioxide in the atmosphere than Earth — about 350 parts per million on the desert planet compared with 417 parts per million on Earth. But Dune has far more ozone in its lower atmosphere: 0.5 percent of the gases in the atmosphere compared to Earth’s 0.000001 percent.

All that extra ozone is crucial for understanding the planet. Ozone is a powerful greenhouse gas, about 65 times as potent at warming the atmosphere as carbon dioxide is, when measured over a 20-year period. “Arrakis would certainly have a much warmer atmosphere, even though it has less CO2 than Earth today,” Farnsworth says.

In addition to warming the planet, so much ozone in the lower atmosphere could be bad news. “For humans, that would be incredibly toxic, I think, almost fatal if you were to live under such conditions,” Farnsworth says. People on Arrakis would probably have to rely on technology to scrub ozone from the air.

Of course, ozone in the upper atmosphere could help shield Arrakis from harmful radiation from its star, Canopus. (Canopus is a real star also known as Alpha Carinae. It’s visible in the Southern Hemisphere and is the second brightest star in the sky. Unfortunately for Dune fans, it isn’t known to have planets.)

If Arrakis were real, it would be located about as far from Canopus as Pluto is from the sun, Farnsworth says. But Canopus is a large white star calculated to be about 7,200° Celsius. “That’s significantly hotter than the sun,” which runs about 2,000 degrees cooler, Farnsworth says. But “there’s a lot of supposition and assumptions they made in here, and whether those are accurate numbers or not, I can’t say.”

in this climate model, a yellowish planet with large, dark brown mountain ranges mostly ringing its poles rotates. Wispy white clouds encircle the equator and poles growing lighter and heavier with changing seasons. Small white arrows indicate the direction winds are projected to blow.
A climate model of Arrakis predicts that cloud cover and other factors would make higher latitudes unbearably hot in summer and well below freezing in the winter. Tropical latitudes would be slightly more comfortable but beset by strong winds (white arrows) that whip up massive sand dunes.A. Farnsworth, M. Farnsworth, S. Steinig/The Conversation (CC BY-ND 4.0 DEED)

A livable yet inhospitable world

The climate simulation revealed that Arrakis probably wouldn’t be exactly as Herbert described it.

For instance, in one throwaway line, the author described polar ice caps receding in the summer heat. But Farnsworth and colleagues say it would be far too hot at the poles, about 70° C during the summer, for ice caps to exist at all. Plus, there would be too little precipitation to replenish the ice in the winter. High clouds and other processes would warm the atmosphere at the poles and keep it warmer than lower latitudes, especially in the summertime.

Although Herbert’s novels have people living in the midlatitudes and close to the poles, the extreme summer heat and bone-chilling −40° C to −75° C temperatures in the winters would make those regions nearly unlivable without technology, Farnsworth says.

Temperatures in Arrakis’ tropical latitudes would be relatively more pleasant at 45° C in the warmest months and about 15° C in colder months. On Earth, high humidity in the tropics makes it far warmer than at the poles. But on Arrakis, “most of the atmospheric moisture was essentially removed from the tropics,” making even the scorching summers more tolerable. The poles are where clouds and the paltry amount of moisture gather and heat the atmosphere.

But the tropics on Arrakis pose their own challenges. Hurricane force winds would regularly sandblast inhabitants and build dunes up to 250 meters tall, the researchers calculate.

It doesn’t mean people couldn’t live on Arrakis, just that they’d need technology and lots of off-world support to bring in food and water, Farnsworth says. “I’d say it’s a very livable world, just a very inhospitable world.”

It’s hard to be a giant sandworm

While humans could possibly get by with some help, the planet would probably not be survivable for its most famous residents: the gargantuan sandworms. “It’s hard to envision such a species with thermal tolerance [to live] in such a climate in such an ecosystem,” Farnsworth says.

Gigantic sandworms would also have other problems, says Lewis, the vertebrate paleontologist at Sam Houston State. At up to 400 meters long, the sandworms would be nearly 10 times the length of the biggest dinosaurs. That would be unusual for an animal with a long body, like a worm or snake. “The worm body plan is really common. It has evolved many times over the last 600 million years,” Lewis says. “But none of them have ever been very big.”

For invertebrate worms, the problem is oxygen, Lewis says. Worms often absorb oxygen through their skin to permeate their bodies. The larger the animal, the harder it would be to get oxygen to their internal organs.

Lewis figures that Dune’s giant sandworms must be vertebrates like Zygaspis worms from sub-Saharan Africa. The species that he studies are considerably smaller: about 20 to 30 centimeters long and up to 7 millimeters thick. But that didn’t stop him from imagining what a Dune-sized vertebrate worm might be like.

Worms with bones and muscles could be bigger and stronger than invertebrates, Lewis says, but they would be limited by gravity. Whales can be big because they live in water, where buoyancy can do a lot of the heavy lifting. “But if you’re going to be on the surface, then you have to be able to fight gravity,” Lewis says. To reach more than about 150 meters long, “you would basically have to be a big ball of bone to keep from crushing under your own weight.”

Perhaps if Arrakis’ worms had skeletons made of superlight material that’s unknown on Earth, they could grow to such enormous size. But that poses a problem for moving around. “The bigger you get, the relatively weaker the muscles are, and so you’d need monstrously strong muscles” and “unbelievably thick bones” to attach them to, Lewis says. And muscles generate a lot of heat.

Zygaspis worms can tolerate 45° C temperatures in the Kalahari Desert because they are small and have lots of surface area relative to their tiny size to shed heat, he says. But a giant sandworm wouldn’t be able to dump heat so readily: The bigger an animal is, the more volume it has to generate and store heat relative to the surface area it has to cool it. Combine the geometry problem with the weather and that spells trouble for colossal worms. “If you’re a giant worm, a hot climate is not your friend,” Lewis says.

If you’re a Dune fan contemplating the realities of life on Arrakis, you’re in luck. The planet would be a feasible, if harsh, place for humans to live. And the bonus is that you probably wouldn’t have to worry about getting eaten by a giant sandworm.

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