3 proofs that debunk flat-Earth theory | Big Think Top Ten 2018 | Michelle Thaller | Big Think

TL;DR

There are numerous proofs that the Earth is round, including observations of boats disappearing over the horizon, the angle of the sun in different cities, and the shape of shadows during a lunar eclipse.

Transcript

So, Oscar, you asked the question, "What are some of the easiest ways that you can prove that the Earth is round?" Because apparently, this is something that we're debating—I have no idea why. That's a hard thing for me to even start talking about because there are so many proofs that the Earth is round, it's difficult to know where to start. And i... Read More

Key Insights

• 😎 The Earth's round shape is supported by various proofs, including observations of boat disappearance and the angle of the sun.
• 🧑‍🔬 Ancient Greek scientists, such as Eratosthenes, made significant contributions to understanding the Earth's spherical nature.
• 💠 The shape of shadows during a lunar eclipse provides further evidence of the Earth's roundness.
• 🤪 Denying the Earth's round shape goes against centuries of scientific knowledge.

Questions & Answers

Q: How can observing boats disappearing over the horizon prove that the Earth is round?

When a boat moves farther away, its bottom disappears first, and eventually, only the top of the mast is visible. This occurs due to the curved nature of the Earth's surface.

Q: How did ancient Greeks measure the Earth's circumference and prove its round shape?

Greek scientist Eratosthenes noticed that the angle of the sun was different between two cities, Syene and Alexandria, and calculated the Earth's circumference based on this observation. The accuracy of his measurement supports the Earth's spherical shape.

Q: Why does the angle of the sun in different cities on the same date indicate a round Earth?

If the Earth were flat, the angle of the sun would be the same everywhere. However, the varying angles observed in different cities suggest that the Earth is curved.

Q: How does the shape of shadows during a lunar eclipse confirm the Earth's round shape?

During a lunar eclipse, the Earth casts a shadow on the moon, which appears curved. This curved shadow is evidence of the Earth's spherical shape, as a sphere is the only shape capable of casting a curved shadow from any direction.

Summary & Key Takeaways

• The Earth's round shape can be confirmed by observing boats disappearing over the horizon as they move farther away.

• The angle of the sun in different cities on the same date provides evidence of the Earth's curvature.

• During a lunar eclipse, the curved shadow of the Earth on the moon demonstrates its spherical shape.