For its historical development, see Spherical Earth. For its determination, see Arc measurement.
Distance from the Earth surface to a point near its center
Earth radius
Cross section of Earth's Interior
General information
Unit system
astronomy, geophysics
Unit of
distance
Symbol
R🜨, ,
Conversions
1 R🜨in ...
... is equal to ...
SI base unit
6.3781×106 m[1]
Metric system
6,357 to 6,378 km
English units
3,950 to 3,963 mi
Geodesy
Fundamentals
Geodesy
Geodynamics
Geomatics
History
Concepts
Geographical distance
Geoid
Figure of the Earth (radius and circumference)
Geodetic coordinates
Geodetic datum
Geodesic
Horizontal position representation
Latitude / Longitude
Map projection
Reference ellipsoid
Satellite geodesy
Spatial reference system
Spatial relations
Vertical positions
Technologies
Global Nav. Sat. Systems (GNSSs)
Global Pos. System (GPS)
GLONASS (Russia)
BeiDou (BDS) (China)
Galileo (Europe)
NAVIC (India)
Quasi-Zenith Sat. Sys. (QZSS) (Japan)
Discrete Global Grid and Geocoding
Standards (history)
NGVD 29
Sea Level Datum 1929
OSGB36
Ordnance Survey Great Britain 1936
SK-42
Systema Koordinat 1942 goda
ED50
European Datum 1950
SAD69
South American Datum 1969
GRS 80
Geodetic Reference System 1980
ISO 6709
Geographic point coord. 1983
NAD 83
North American Datum 1983
WGS 84
World Geodetic System 1984
NAVD 88
N. American Vertical Datum 1988
ETRS89
European Terrestrial Ref. Sys. 1989
GCJ-02
Chinese obfuscated datum 2002
Geo URI
Internet link to a point 2010
International Terrestrial Reference System
Spatial Reference System Identifier (SRID)
Universal Transverse Mercator (UTM)
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Earth radius (denoted as R🜨 or ) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid, the radius ranges from a maximum of nearly 6,378 km (3,963 mi) (equatorial radius, denoted a) to a minimum of nearly 6,357 km (3,950 mi) (polar radius, denoted b).
A nominal Earth radius is sometimes used as a unit of measurement in astronomy and geophysics, which is recommended by the International Astronomical Union to be the equatorial value.[1]
A globally-average value is usually considered to be 6,371 kilometres (3,959 mi) with a 0.3% variability (±10 km) for the following reasons.
The International Union of Geodesy and Geophysics (IUGG) provides three reference values: the mean radius (R1) of three radii measured at two equator points and a pole; the authalic radius, which is the radius of a sphere with the same surface area (R2); and the volumetric radius, which is the radius of a sphere having the same volume as the ellipsoid (R3).[2] All three values are about 6,371 kilometres (3,959 mi).
Other ways to define and measure the Earth's radius involve the radius of curvature. A few definitions yield values outside the range between the polar radius and equatorial radius because they include local or geoidal topography or because they depend on abstract geometrical considerations.
^ abMamajek, E. E; Prsa, A; Torres, G; et al. (2015). "IAU 2015 Resolution B3 on Recommended Nominal Conversion Constants for Selected Solar and Planetary Properties". arXiv:1510.07674 [astro-ph.SR].
^Cite error: The named reference Moritz was invoked but never defined (see the help page).
Earthradius (denoted as R🜨 or R E {\displaystyle R_{E}} ) is the distance from the center of Earth to a point on or near its surface. Approximating the...
earthshine is [ Earth albedo × (Earthradius / Radius of Moon's orbit)2 ] relative to the direct solar illumination that occurs for a full moon. (Earth albedo...
and shape of the Earth. The simplest model for the shape of the entire Earth is a sphere. The Earth'sradius is the distance from Earth's center to its surface...
the average radius of Jupiter, 109 times the radius of the Earth, and 1/215th of an astronomical unit, the approximate distance between Earth and the Sun...
be related to the equatorial radius and the polar radius, respectively a and b (see: Earth polar and equatorial radius of curvature). Then, the flattening...
are in LEO, with an altitude never more than about one-third of the radius of Earth (or about 2000 kilometers). The term LEO region is also used for the...
The Jupiter radius or Jovian radius (RJ or RJup) has a value of 71,492 km (44,423 mi), or 11.2 Earth radii (R🜨) (one Earthradius equals 0.08921 RJ)....
See Figure of the Earth and Earthradius § Global radii for details. Recent measurements from satellites suggest that Earth is actually slightly pear-shaped...
values, such as the mass, radius, and rotation of Earth. The measurement is also useful in characterizing the lunar radius, as well as the mass of and...
of the Earth in the 17th century were based on a circumference estimate of 60 miles (97 km) to the degree of latitude, corresponding to a radius of 5,500 km...
osculating sphere. With respect to Earth, the center of the true horizon is below the observer and below sea level. Its radius or horizontal distance from the...
layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 19% of Earth'sradius [0.7% of volume] or...
on the surface of the Earth, d is depth and R is the radius of the Earth. If the density decreased linearly with increasing radius from a density ρ0 at...
latitudinal changes in the Earth's magnetic field, sudden ionospheric disturbances, polar cap absorption, variation in the Earthradius of ± 11 km from equator...
}{180}}M_{r}\cos \phi \!} where Earth's average meridional radius M r {\displaystyle \textstyle {M_{r}}\,\!} is 6,367,449 m. Since the Earth is an oblate spheroid...
atmosphere is thin relative to the Earth'sradius—especially the dense atmospheric layer at low altitudes—the Earth's gravitational acceleration as a function...
atmosphere and outer space. The Kármán line, at 100 km (62 mi) or 1.57% of Earth'sradius, is often used as the border between the atmosphere and outer space...
radius or the gravitational radius is a physical parameter in the Schwarzschild solution to Einstein's field equations that corresponds to the radius...
planets. Objects must orbit Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun. Earth, along with the Solar System...
(February 2023). "Evidence for the volatile-rich composition of a 1.5-Earth-radius planet". Nature Astronomy. 7 (2): 206–222. arXiv:2212.08477. Bibcode:2023NatAs...
present sea level, comparing sea levels in the past with the level today. Earth'sradius at sea level is 6,378.137 km (3,963.191 mi) at the equator. It is 6...
the assumption that Earth is flat. In the 2nd century CE, Ptolemy estimated the mean distance of the Sun as 1,210 times Earth'sradius. To determine this...
Global Information
