Figure of the Earth - Wikipedia
In geodesy, the figure of the Earth is the size and shape used to model planet Earth. The kind of figure depends on application, including the precision needed for the model. A spherical Earth is a well-known historical approximation that is satisfactory for …
Strange but True: Earth Is Not Round | Scientific American
2007年4月12日 · Isaac Newton first proposed that Earth was not perfectly round. Instead, he suggested it was an oblate spheroid—a sphere that is squashed at its poles and swollen at the equator. He was correct...
Is the Earth round? - NOAA's National Ocean Service
While the Earth appears to be round when viewed from the vantage point of space, it is actually closer to an ellipsoid. However, even an ellipsoid does not adequately describe the Earth’s unique and ever-changing shape. Our planet's diameter bulges at the equator due to the centrifugal force created by the earth’s constant rotation.
The Earth is not round (but it’s not flat either) - BBC
2016年6月3日 · So what is the true shape of our planet? And if it’s not perfectly spherical, could there be anything else in the Universe that is? Watch the one-minute animation above to find out.
90 Years of Our Changing Views of Earth - NASA
2020年12月21日 · Indirect evidence of the Earth’s spherical shape has existed for a long time, but the photographic proof was lacking until well into the 20th century. The ancient Greeks believed the Earth was round and calculated its circumference with remarkable accuracy, while observers inferred our planet’s spherical shape as it cast a curved shadow on ...
Ellipsoid/Spheroid – Our Oblate Spheroid Planet Earth
A datum describes the shape of the Earth in mathematical terms. A datum defines the radius, inverse flattening, semi-major axis, and semi-minor axis for an ellipsoid. Here is the WGS84 datum:
Spherical Earth - Wikipedia
Earth's shape can be thought of in at least two ways: as the shape of the geoid, the mean sea level of the world ocean; or; as the shape of Earth's land surface as it rises above and falls below the sea.
Earth’s True Form: Exploring the Actual Shape of Our Planet
2024年2月15日 · Geoid: Earth’s True Shape: Imagine a lumpy potato floating in space—that’s a closer representation of Earth’s actual shape! The geoid is a mathematical model that defines Earth’s shape as an irregular and undulating surface, taking into account variations in gravitational pull and sea level across the planet.
How we discovered the true shape of the Earth
French philosopher René Descartes’s theories about vortices in the ether suggested Earth was shaped like an upright egg, stretched towards the poles. Meanwhile, Isaac Newton ’s theory of …
2.4 The Nearly Spherical Earth | GEOG 160: Mapping our …
A geoid is the equipotential surface of the Earth's gravity field; put simply, it has the shape of a lumpy, slightly squashed ball. Determining the precise shape of the geoid is a major concern of the science of geodesy, the study of Earth’s size, shape, and gravitational and magnetic fields.