How Do We Know the Earth Isn't Flat

How do we know the Earth isn’t flat? For thousands of years people have known the Earth is round. Ancient civilizations used the stars and shadows to figure it out. Mariners confirmed it by sailing around the globe. And when the space age began, we saw it with our own eyes — the Earth is round! A NASA scientist explains how we’ve known for centuries that our planet is a sphere. Explore more: https://www.nasa.gov/history/90-years-of-our-changing-views-of-earth/ Producers: Scott Bednar, Pedro Cota, Jessie Wilde Editor: Credit: NASA

What is said in the film

How do we know the Earth isn’t flat? We Asked a NASA Scientist. That's a great question. In fact, two or three thousand years ago, ancient people on this planet that did great things figured out that the Earth was round, it was a sphere. This was a magical revelation for the Greeks and the Egyptians, who were able to see from the motions of the stars and the way the Sun moved.

They saw the way the Sun's shadow worked in different places. And they figured, well, that's only possible if the Earth is round. And they took that information and it extended into the time of the great mariners that explored our Earth by ships. They made the first orbit of Earth by sea, and they knew the Earth was round, allowing them to go across one ocean and come back home the other way. If the Earth were flat, they would have sailed off the end.

And so we knew that. But then, at the dawn of the space age, in the late 50s and 60s, we were able to see for ourselves that our beautiful home is a gorgeous round object known as a sphere. And that was really special. It put ourselves into context of our solar system and our universe. We have a big round Sun and a beautiful round Earth and a round Mars.

And today we use the roundness of Earth, the spherical Earth, to use methods in space geodesy to figure out where we are, where we're going. I haven't been lost in years. That's pretty good. What's happening to the Earth, what's happening to our oceans as we take the pulse of our planet and consider other worlds beyond as we explore those. So as we get ready to go back to the Moon with women and men and explore other worlds, the roundness of our solar system and our universe is a special thing.

And we should embrace that as we understand why our planet isn't flat. We Asked a NASA Scientist. NASA. A NASA 360 Production.

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