Flat Earth
The Earth is an oblate spheroid, a sphere slightly flattened at the poles and bulging at the equator. This has been established by multiple independent lines of evidence spanning over 2,000 years, from ancient Greek geometry to modern satellite imagery and GPS systems.
What we know
The spherical shape of Earth was understood by ancient Greek scholars including Pythagoras, Aristotle, and Eratosthenes, who calculated Earth's circumference with remarkable accuracy around 240 BCE using shadow angles. Eratosthenes' method has since been reproduced many times and yields consistent results confirming a spherical Earth.
Multiple independent observational phenomena confirm Earth's shape: ships disappear hull-first over the horizon; different constellations are visible from different latitudes; Earth's shadow on the Moon during lunar eclipses is always circular regardless of orientation; and the time-zone system works precisely as predicted by a rotating spherical planet. GPS, satellite communications, and intercontinental flights all operate using algorithms based on a spherical (technically oblate spheroid) Earth, any significant deviation would cause these systems to fail.
Since the space age, thousands of photographs and videos taken by dozens of independent space agencies, private companies, and amateur high-altitude balloon flights have all depicted a spherical Earth. The Earth's precise shape is routinely measured by geodetic satellites, showing it is an oblate spheroid with a polar radius of 6,357 km and equatorial radius of 6,378 km.
Flat Earth claims, including assertions that space agencies globally have coordinated a deception for unknown purposes, require the complicity of hundreds of thousands of engineers, scientists, pilots, and amateur astronomers worldwide, with no single confirmed whistleblower or piece of physical evidence. No scientific society or peer-reviewed journal accepts flat-Earth claims as having any observational basis.
Common claims
- The Earth appears flat, therefore it is flatIncorrect, the scale of Earth's curvature is imperceptible at ground level but measurable at altitude and confirmed by shadow geometry
- NASA and all space agencies fake images of a spherical EarthNot supported, independent agencies, private companies, and amateur balloonists have all photographed Earth's curvature
- Pilots would notice if the Earth were curvedFalse, pilot navigation and flight paths are designed for a spherical Earth and would not work on a flat plane
- Ships disappearing hull-first at sea is an optical illusionFalse, the phenomenon is well-explained by Earth's curvature and is reproducible