Question

Why the earth is round but not flat

Answer 1

However, since 1968, we’ve used our spacecraft and satellites to take literally thousands of photos of Earth, and from every angle. Each shot shows Earth like Earthrise did. That’s only possible if Earth is a disk in three dimensions — a sphere. Today, astronauts like Scott Kelly even show us the curve of the Earth in real-time. He sees a sunrise every 90 minutes, a phenomenon impossible with a disk.

Answer 2

Humanity has known the Earth to be round for a few millenia and I’ve been meaning to refine that video and show more of these methods of how we figured out the world is not flat. I’ve had a few ideas on how to do that, but recently got an interesting incentive, when Phil Plait (The Bad Astronomer) wrote about a recently published BBC article about “The Flat Earth” society. Phil claims it’s ridiculous to even bother rebutting the flat earth society – and I tend to agree. But the history of our species’ intellectual pursuit is important and interesting, and it’s very much well worth writing about. You don’t need to denounce all science and knowledge and believe in a kooky conspiracy theory to enjoy some historical factoids about humanity’s quest for space.