The world's most famous astrophysicist has confirmed the long-held belief that the Earth is round.
Neil deGrasse Tyson debunked 'flat Earth theory' in a new video on his YouTube channel. In it, he spoke with comedian Chuck Nice about the overwhelming scientific evidence that our planet is spherical in shape.
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"We have video from space of the rotating, spherical Earth," Tyson says. "The Earth is round."
After pretending to end the conversation after that definitive statement, the co-hosts went on to discuss how some people had come to believe in a flat planet.
'Flat-Earthers' are a small group who have gained notoriety in recent years for their unsubstantiated claims that the Earth's roundness is a conspiracy, and that the truth of the planet's shape is being withheld from the public.
"What's odd is there are people who think that Earth is flat but recognize that the moon is round," Tyson says.
"Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and the sun are all spheres. But Earth is flat ... something doesn't square here."
He explained the physics around why heavenly bodies tend to be spherical, which he wrote about at length in his book Astrophysics for People in a Hurry.
"All the laws of physics and the accounting of energy as processes unfold in the universe…they conspire to make things round."
Bodies that have a flatter shape have been compressed because they rotate extremely fast, which the Earth does not.
"Almost everything in the universe is either spheres or slight distortions of a sphere."
As evidence, he cited the lunar cycle which everyone can observe.
"If you see the shape of Earth's shadow on the moon, it is always round. If Earth were flat, sometimes you'd get a flat shadow. Who's ever seen a flat shadow?"
"The only thing that makes a perfect circle shadow every time is a perfect sphere."
While Christopher Columbus is commonly credited with proving the Earth's roundness by crossing the Atlantic Ocean in the 15th century, Tyson says the Ancient Greeks knew they were living on a sphere thousands of years prior.
He mentioned Eratosthenes' famous well experiment to calculate the circumference of the planet, as well as seafarers who would observe ships disappearing beyond the horizon as evidence of a rounded Earth.
He says the rise of flat earth theory indicates two things: the right to free speech, and America's "failed education system".
"Our system needs to train you in not only what to know, but how to think about information and knowledge and evidence," Tyson says.
"If you don't have that kind of training, you'd run around believing anything."