A representation of the Earth's shape, released by NASA, generated significant buzz on social media due to its large undulations. However, this visualization does not correspond to the actual physical shape of the planet, as it illustrates the concept of the geoid, a scientific model that demonstrates minuscule disparities in the Earth's gravitational field.
Details of the Scientific Disclosure
This material was presented on July 15th by the Goddard Space Flight Center, which belongs to NASA, and was mistakenly interpreted as the authentic appearance of the planet. The creation of this image was based on a model developed from over one billion measurements collected over fifteen years.
The representation uses data from the GOCO06s model, which was constructed using information from space missions such as GRACE, also from NASA, and GOCE, operated by the European Space Agency. The fundamental purpose of this model is to make perceptible those gravitational changes that would otherwise be imperceptible to the human eye under normal conditions.
How the Geoid and Gravity Work
The geoid serves as a reference point based on a hypothetical sea level that would extend across the entire Earth's surface, assuming there were no influences from currents, tides, or winds. It maps how the planet's mass distribution affects the intensity of gravity in different regions.
Despite the irregular appearance shown, the Earth does not have a 'potato-like' shape. The depressions and elevations seen in the model are merely reflections of small gravitational variations, resulting from the uneven distribution of materials within the planet. Areas with a higher concentration of denser substances, such as rocks or magma, generate slightly stronger gravitational attraction, resulting in elevated regions in the model. Conversely, areas with lower density exhibit opposite effects, forming lower areas.
Variations and Practical Applications
NASA clarifies that these variations can reach about 85 meters near Iceland and approximately 106 meters south of India. Even after the visual magnification used in the image, such differences remain insignificant when compared to the global dimensions of the Earth. The geoid model has practical utility in various scientific fields. According to data provided by the United States Geological Survey (USGS), this irregular sea level facilitates more accurate calculations regarding the depth of earthquakes and other bodies located beneath the surface.
It is important to note that the geoid differs from the ellipsoid, another model used to study the planet. While the ellipsoid offers a more uniform mathematical shape, which simplifies cartographic calculations, the geoid integrates the fluctuations of the gravitational field, providing a reference more aligned with the planet's real conditions. Therefore, the image released by NASA should be viewed as a scientific tool designed to amplify subtle changes in Earth's gravity, and not as a representation of a new physical shape of the planet.
