NASA has published a visualization of Earth’s geoid, showing how variations in the planet’s gravity field shape a hypothetical level sea surface. Its invisible hills and valleys are not features of Earth’s physical outline. They represent differences in gravitational potential, made visible through vertical exaggeration.
NASA’s Goddard Space Flight Center produced the image using the GOCO06s global gravity model. It depicts a scientific reference surface, not a literal view of the planet. The geoid is an equipotential surface that approximates the level mean sea surface gravity alone would produce, without tides, winds or currents. Its uneven form reflects regional differences in mass distribution, including changes in crustal structure and mantle composition, as well as ocean depth and topography.
The geoid’s rises and dips reflect variations in Earth’s gravitational field. A model turns those subtle differences into a shape that can be examined visually. Without exaggeration, they would be difficult to see at planetary scale. The displayed terrain represents gravitational potential, not a deformation of Earth’s surface.
GOCO06s was developed through the Gravity Observation Combination project, combining satellite and terrestrial gravity information. Its inputs include observations from NASA’s Gravity Recovery and Climate Experiment (GRACE) and the European Space Agency’s Gravity Field and Steady-State Ocean Circulation Étudier (GOCE). The missions made complementary measurements: GRACE was especially useful for tracking changes in mass distribution over time, while GOCE was designed to measure the static gravity field and geoid in detail. Gravity models express these variations through spherical-harmonic coefficients rather than maps of the planet’s visible surface.
The geoid differs from the reference ellipsoid used in mapping and satellite positioning. An ellipsoid is a smooth mathematical approximation of Earth’s average size and flattening. The geoid is irregular because it follows variations in gravity. Geodetic systems use the separation between the ellipsoid and geoid to convert satellite-derived ellipsoidal heights into elevations tied to mean-sea-level-based datums.
Despite its unusual appearance, the geoid does not mean Earth is shaped like a “potato.” It visualizes the gravitational field produced by the planet’s unevenly distributed mass. Those variations affect sea-level references and satellite orbits. Geoid models also provide a practical basis for surveying, mapping, engineering and Earth observation.
Accurate geoid models support satellite positioning and elevation measurement, as well as engineering projects that depend on reliable height data. They help researchers interpret changes in mass distribution, including shifts linked to ice loss and groundwater, along with changes in ocean mass. By combining satellite observations with other gravity measurements, models such as GOCO06s give a more precise account of Earth’s gravitational field.
