The Moon isn't round—it's shaped like a slightly lopsided egg
Viewed from Earth, the Moon appears as a neat circle, but gravitational interactions shaped it differently. Over billions of years, tidal forces exerted by Earth pulled the Moon's crust into an elongated, egg-like shape. Its smaller, pointier end points toward Earth, and its center of mass sits roughly 2 kilometers off-center.
The Optical Illusion of a Perfect Sphere
From Earth, the full Moon appears as an immaculate, glowing disc. Centuries of skywatching and early telescopic observations reinforced the idea that Earth's natural satellite was a near-perfect sphere orbiting smoothly through space. Even high-resolution photographs taken from low orbit tend to present an image of spherical balance, masking subtle deviations across thousands of kilometers of rocky terrain.
In reality, the Moon is an irregular ellipsoid rather than a true sphere. It is distorted along several axes, featuring an elongated profile that stretches in the direction of Earth and flattened regions at its poles. If viewed along its equatorial plane with its topographical variations exaggerated, the Moon resembles a slightly asymmetrical egg, with its narrower, more prominent end permanently directed toward the planet it orbits.
How Gravity Molded the Early Moon
The distortion of the Moon's shape is the direct result of gravitational interaction with Earth during the solar system's early history. Shortly after forming from the debris of a massive collision, the young Moon was much closer to Earth and composed of semi-molten rock and magma. In this pliable state, the gravitational pull of Earth exerted strong tidal forces across the lunar body.
Earth's gravity pulled harder on the near side of the Moon than on the far side, creating a pronounced tidal bulge along the Earth-Moon axis. At the same time, the rotational forces of the spinning Moon flattened its polar regions. As the Moon cooled, solidified, and receded into a wider orbit, these deformations became permanently frozen into its lithosphere. Planetary scientists refer to this preserved shape as a fossil bulge, an ancient structural signature of forces that acted billions of years ago.