What shape is the planet known as Earth?

Oblate spheroid is the closest shape we can name for Earth.

Earth is actually not a perfect sphere.

The gravity of the moon causes tidal forces on Earth's oceans to bulge along the equator. This makes Earth's shape spheroid (think of a squishing a balloon on the top and bottom to make the center more fat).

Earth is not a perfect sphere, but it's close enough to not make any difference.

The diameter of Earth at the equator is 12,756.2 kilometers.

The diameter of Earth through the poles is 12,713.6 kilometers.

That's a difference of only 42.6 kilometers out of more than 12,700 kilometers. Percentage-wise that's a difference of only one-third of 1 percent! One-third of 1 percent is the manufacturing standard for billiard balls. And, you know that pool players world-wide would scream bloody murder if their billiard balls did not roll true.

So, as I said, Earth is not a perfect sphere, but it's close enough to not make any difference.

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What is the shape of ALL planets? Round like a ball.

As chris p. very well explained, the earth is not a perfect sphere.

More commonly, it looks like an orange, squeezed slightly from the top!

It's of oblate shape.

and so there is a saying. the moment of inertia of the earth is a maximum about the polar axis and minimum about an axis in the equatorial plane.

What shape is a pancake?

Ummm...a sphere?