I WONDER - How Many Surfaces Does A Sphere Have?

The video explains that a sphere is a perfectly round shape with no corners or edges, making it unique among shapes for having no flat surfaces. It also clarifies that while the Earth appears spherical, it is actually a spheroid due to the slight flattening at the poles.

What does it mean for a shape to have no flat surfaces?

How does the shape of the Earth challenge the common perception of it being a sphere?