Earthsized

Earthsized is a term used in planetary science and astronomy to describe objects whose size is comparable to Earth. It is most commonly applied to exoplanets, but may also refer to planetary bodies within the Solar System when their diameter approaches Earth's.

There is no single formal boundary for Earth-sized; definitions vary. A common practical range is about 0.8 to 1.25 Earth radii, though some researchers extend roughly from 0.5 to 1.5 Earth radii. Radius is the principal metric, while mass and density can differ substantially.

In exoplanet studies, Earth-sized does not imply Earth-like conditions. Planets within this size range can have diverse compositions, from rocky to water-rich, with a wide range of surface conditions and atmospheric properties.

The term is widely used in catalogues and press material to convey scale, but it can mislead about habitability or geophysical similarity. Some propose standardized bounds to reduce ambiguity.

See also Earth radius, exoplanet, Earth-like planet, habitable zone.