The Sun isn't actually a perfect circle. It's slightly flattened at the poles and bulging at the equator, making it more of an oblate spheroid.

Here's why:

* Rotation: The Sun rotates on its axis, causing it to bulge at the equator due to centrifugal force (the outward force that objects experience when rotating).

* Gravity: The Sun's massive gravity pulls everything towards its center, but the centrifugal force due to rotation counteracts this pull slightly at the equator.

This flattening is subtle, making the Sun appear nearly circular from Earth. We only see the Sun's disc, which is a projection of its 3D shape onto the 2D plane of the sky.

Fun fact: The Sun's rotation period is about 25 days at the equator and 36 days at the poles! This difference in rotation speed further contributes to its oblate shape.