NASA releases 'Lumpy Earth' renderings

NASA’s new “lumpy Earth” visual is not a new picture of the planet’s surface. The rendering shows the geoid — an idealized global surface shaped by Earth’s gravity field — and NASA says it has exaggerated the height differences by a factor of 10,000 to make them visible. The agency’s Scientific Visualization Studio published the geoid visualization in late July, and a NASA-linked YouTube video posted on Aug. 5 pushed the imagery to a wider audience. The model is based on GOCO06s, a satellite-only global gravity field model built from more than a billion observations collected over 15 years from 19 satellites, including NASA’s GRACE mission and the European Space Agency’s GOCE mission. ### If this is not Earth’s actual shape, what is NASA showing? The geoid is “an equipotential surface” that can be thought of as the shape the ocean surface would take under Earth’s gravity field, NASA’s Scientific Visualization Studio says. That means the image is not a topographic map of mountains and trenches, and it is not a photograph of the planet from space. NASA says Earth’s mass is not distributed evenly, and those differences in mass change the strength of gravity from place to place. (svs.gsfc.nasa.gov) Older NASA visualization material describing gravity mapping says areas with less mass, such as ocean basins, appear blue, while places with greater gravitational pull appear red. ### Why does the planet look like a potato in the rendering? NASA says the apparent bulges and dips are heavily amplified for visibility. (svs.gsfc.nasa.gov) On the Scientific Visualization Studio page for “The Geoid,” the agency says the height is exaggerated by a factor of 10,000 and labels the product “not to scale.” The actual range in the model is much smaller than the image suggests. NASA says the geoid height in this visualization runs from about +85 meters near Iceland to about -106 meters near southern India. (svs.gsfc.nasa.gov) ### Where did the data come from? NASA’s visualization page says the geoid height comes from GOCO06s, a satellite-only global gravity field model produced by the Gravity Observation Combination project. The agency says the model is based on more than a billion observations gathered over 15 years from 19 satellites. (svs.gsfc.nasa.gov) Those satellites include NASA’s Gravity Recovery and Climate Experiment, or GRACE, and ESA’s Gravity field and steady-state Ocean Circulation Explorer, or GOCE, according to NASA. (svs.gsfc.nasa.gov) NASA’s older geodesy material says precise knowledge of the geoid is needed to make sea-level measurements from space. ### What does this have to do with oceans and sea level? NASA’s geodesy explainer says scientists need a carefully constructed geoid to measure sea level accurately from satellites. (svs.gsfc.nasa.gov) Because the geoid represents the gravity-shaped reference surface of the ocean, it gives researchers a baseline for separating true sea-surface changes from the planet’s uneven gravity field. NASA’s Earth visualization materials also frame this kind of work as part of a broader effort to turn hard-to-see Earth system data into graphics the public can inspect and download. (svs.gsfc.nasa.gov) The agency’s visualization pages say such products are built to improve understanding of Earth science phenomena and measurements. ### Why is NASA resurfacing this now? The Aug. 5 YouTube post and recent NASA Scientific Visualization Studio entry indicate the agency is recirculating geoid science through newer rendering tools and distribution channels. (svs.gsfc.nasa.gov) NASA’s current page presents multiple versions of the same model, including a to-scale view and exaggerated versions designed to make subtle gravity-driven differences legible on screen. That suggests the immediate next step for viewers is not a new mission announcement, but access to the downloadable visualization files and metadata NASA has already posted on the Scientific Visualization Studio page. (nasa.gov) (youtube.com)