Flat Earth refers to the belief that the Earth is a flat, disc-like plane rather than an oblate spheroid. The position stands in contrast to the heliocentric model and the broader framework of modern astronomy and physics, which holds that the Earth is roughly spherical. Flat Earth claims range from informal skepticism of official scientific narratives to fully elaborated alternative cosmologies with their own internal models of gravity, celestial mechanics, and geography.
The question of Earth's shape is not treated as an open scientific question within mainstream institutions. Geodesy, satellite imaging, aviation, maritime navigation, and physics all operate on the assumption of a spherical - more precisely, oblate spheroidal - Earth, and the predictive success of those fields is frequently cited as evidence. Photographs from space, the behavior of ships disappearing hull-first over the horizon, circumnavigation, time zones, eclipses, and the physics of gravity are among the phenomena that proponents of a spherical Earth argue are incompatible with a flat model.
Flat Earth proponents dispute many of these claims on methodological grounds. Common objections include skepticism of space agency imagery, arguments that perspective and atmospheric refraction explain horizon phenomena, and challenges to the reliability of official sources. Some proponents argue that the spherical Earth model is sustained by institutional interest rather than independently verifiable evidence. The movement has grown in visibility since the mid-2010s, aided substantially by social media and documentary content.1)
Flat Earth adherents do not hold a single unified cosmology. Models vary significantly on the arrangement of continents, the nature and location of the sun and moon, the mechanism producing day and night, and the structure of what lies beyond the disc's edge - commonly posited as an ice wall or dome. These internal disagreements mean flat Earth is more accurately described as a category of dissenting cosmological views than as a single coherent theory.
The scientific consensus that Earth is an oblate spheroid is documented across astronomy, geodesy, physics, and related fields. For a structured overview, see the Scientific Consensus on Earth's Shape.
1. National Aeronautics and Space Administration. “Earth Fact Sheet.” NASA Goddard Space Flight Center. https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html 2. Garwood, Christine. Flat Earth: The History of an Infamous Idea. Macmillan, 2007. 3. International Association of Geodesy. Geodetic Reference System 1980. IAG Special Publication, 1980; updated standards available via https://www.iag-aig.org 4. Rawlins, Dennis. “The Eratosthenes Experiment.” DIO: The International Journal of Scientific History, various volumes.