Planetary shape refers to the form of celestial bodies, primarily planets, which are generally spherical due to gravity. As a planet forms, its mass pulls material toward its center, creating a shape that minimizes gravitational potential energy. This results in a round shape, although some planets may be slightly flattened at the poles and bulging at the equator, a phenomenon known as oblateness. The shape of a planet can also be influenced by its rotation. For instance, Earth is not a perfect sphere but an oblate spheroid because it spins on its axis. Other factors, such as tidal forces and geological activity, can also affect a planet's shape over time.