Earth ellipsoid
An earth ellipsoid means that the Earth is not a perfect sphere but it is actually shaped like a big ball which is flattened at the top and bottom areas. Imagine a ball that is a little bit squished from the top and bottom but it still looks like a ball.
This is because the Earth spins around an imaginary line that goes through its center which causes the equator to bulge out a little bit and the poles to be slightly flattened.
Because the Earth is so big, it is hard to notice the difference between the poles and the equator by just looking at it but scientists have carefully measured it and have found that the Earth is about 21 kilometers wider at the equator than it is at the poles.
So just like when you try to spin a ball really fast and it changes shape a little bit, the Earth is shaped like a slightly flattened ball because of the way it spins.
This is because the Earth spins around an imaginary line that goes through its center which causes the equator to bulge out a little bit and the poles to be slightly flattened.
Because the Earth is so big, it is hard to notice the difference between the poles and the equator by just looking at it but scientists have carefully measured it and have found that the Earth is about 21 kilometers wider at the equator than it is at the poles.
So just like when you try to spin a ball really fast and it changes shape a little bit, the Earth is shaped like a slightly flattened ball because of the way it spins.
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