Three proofs that Earth is round with NASA’s Michelle Thaller

“It’s not okay to think that the Earth is flat. This is not a viable argument,” explains Dr. Michelle Thaller, astronomer and science communicator with the NASA Goddard Space Flight Center. So how do we know the Earth is round? Watch this 2018 Big Think explainer: Three proofs that debunk the flat-Earth theory.

…people have known of this for way more than 2,000 years. The ancient Greeks actually had a number of really elegant, wonderful proofs that the Earth was a sphere.

Listen as Thaller describes three observable ways that humans have come to know that we live on a sphere, or specifically, an irregularly-shaped ellipsoid:

• Looking at ships or boats on the horizon with binoculars.
• Eratosthenes‘ measurements of sunlight down wells in two different cities.
• Aristarchus‘ observations of Earth’s shadow on the moon during lunar eclipses.

It’s a useful video for older learners and adults who want to understand the shape of our Blue Marble home, or need to explain it to others. She also summarizes with this:

…with binoculars you can see planets, you can see Saturn and Jupiter, you can see Mars with a telescope, the sun and the moon, everything else you see in the solar system is a sphere.

So we’re the one thing that is different?

Watch these related videos next:
• Everything You Need to Know About Planet Earth
• What Does Earth Look Like From Space? An Astronaut’s Perspective
• Why do people fall for misinformation?

Bonus: The Overview Effect.