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Sometime in the next few weeks, a California man named “Mad” Mike Hughes will launch himself 1,800 feet into the air for a mile-long ride in a homemade, steam-powered metal rocket. His goal: To prove the earth is flat.

Wait, is the Earth flat?

If you thought that matter was settled some time ago by NASA, you’re not alone. If you’re convinced that the images of our spherical planet beamed down from space are an elaborate conspiracy, you’re also not alone. Google searches for “flat earth” have more than tripled in the past two years, the Economist reports.

The flat-earth movement is having a moment. On Nov. 9, 500 “flat earthers” gathered in North Carolina for the Comic Con of conspiracy theories, the first annual Flat Earth International Convention. In September, Bobby Ray Simmons Jr., a.k.a. the rapper B.o.B, launched a crowdfunding campaign to send satellites into orbit to ascertain the Earth’s shape.

“I don’t believe in science,” Hughes told the AP earlier this month. “I know about aerodynamics and fluid dynamics and how things move through the air, about the certain size of rocket nozzles, and thrust. But that’s not science, that’s just a formula. There’s no difference between science and science fiction.”

You could blame the cultural atmosphere of alternative facts that put a conspiracy theorist in the White House. “Conspiracy theories are appealing because they offer simple explanations for complex phenomena, or because they let people believe they are in possession of secret knowledge that the powerful wish to suppress,” the Economist notes. “They tend to be most popular among less-educated people who do not trust public institutions. They are extremely common in dictatorships, where people assume, often correctly, that the authorities are lying.”

Is the Earth flat? You can test it yourself

British academic Ian Whitaker offers a simple test to put the matter to bed, which could save “Mad” Mike Hughes a spot of trouble. Compare shadows of sticks in the ground at different locations. In one spot where the sun is directly overhead, there will be no shadow. In a spot 500 miles north, for example, the stick will have a shadow. If the earth were flat, both sticks would have no shadow because they would be at the same angle toward the sun. That was good enough for the ancient Greeks, who used it to calculate the circumference of the earth with 90% accuracy in 250 B.C.

“Ultimately, arguing on the internet is not the best way forward for any scientific endeavor,” says Whitaker. “We need to provide the means for people to test these theories themselves and to understand the results they get.”