The Squished Ball
If you hold a ball of clay in your hand and spin it fast, the middle puffs out. That is exactly what happened to our Moon. It used to be much closer to Earth and spun faster, which stretched it like taffy.
Why it Stays That Way
Even though the Moon slowed down over billions of years, its rock was once hot and soft enough to bend. Now that the rock is cold and hard, it keeps that squished shape. It still has a tiny bulge at the sides because of how Earth's gravity pulled on it long ago.
What We Measure
When we measure the Moon from space, we see it is not perfectly round like a basketball. It is wider around its middle than from top to bottom. This makes it an oblate spheroid. Think of it as a football that got pushed in gently at both ends.
Examples
- A basketball looks perfect, but a volleyball is slightly wider around its middle.
- Holding an orange in your hand and gently squeezing it makes it look like a football.
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See also
- How will the Artemis missions help humanity return to the Moon?
- What are tidally locked planets?
- What If We Landed on Mars Instead of the Moon?
- What is Europa?
- What is Earth's magnetic field?