What is oblateness?

Oblateness is how much something gets flattened when it spins around.

Imagine you have a playdough ball, round and squishy. Now, spin it really fast like a top. What happens? It starts to look more like a pancake, wider at the bottom and narrower on the sides. That’s oblateness in action!

Like a Spinning Pancake

Think of Earth as that spinning playdough ball. It spins around once every day, and over time, it got a little flattened, not much, but enough to notice. So Earth is slightly more like a pancake than a perfect sphere.

Now imagine you have a hula hoop and a tennis ball. The hula hoop is very flat, that’s high oblateness. The tennis ball is almost round, that’s low oblateness.

So, the faster something spins, the more flattened, or oblate, it becomes, just like your playdough pancake!

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Examples

  1. Imagine the Earth as a spinning ball of clay that gets slightly flattened at the poles.
  2. A spinning top becomes wider at the base when it spins fast.
  3. If you spin a water balloon, it might stretch out like a pancake.

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