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It is stated that the Earth is a 'squashed sphere' due to the very slight bulge at the equator. (Thought in reality it's such a small difference, it's essentially spherical)

Typical values:

Equatorial Diameter: 12,756 km Meridional Diameter: 12,714 km

I'm looking at why the Earth has this tiny bulge.

Some sources I read talk about the tidal effect from the moon. But others talk about the Earth spinning causing this.

The books I have (and videos I've watched) just talk about this things separately and don't really explain the difference

Surely the bulge due to a mixture of both? which one has a greater effect? Does the rotational bulge not effect the oceans or something? Does the tidal bulge only effect the water? I'm really confused

Qmechanic
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James Kwikje
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1 Answers1

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The bulge is due to the rotation of the earth. The moon does cause “earth tides” that slightly affect the shape of the earth, but this phenomenon is about five orders of magnitude smaller than the equatorial bulge.

Ben51
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