Mass of the Earth

Earth Mass
Common symbols	${\displaystyle M_{\oplus }}$, ${\displaystyle M_{\mathrm {T} }}$, ${\displaystyle M_{\mathrm {E} }}$ or ${\displaystyle E}$
SI unit	kilogram (kg)
Other units	gram (g) [CGS] Solar Mass (M⊙) [IAU]
In SI base units	7024597220000000000♠(5.9722±0.0006)×1024 kg
SI dimension	${\displaystyle [M_{\oplus }]=\mathrm {M} }$ (mass)
Derivations from other quantities	M⊕ = g · R2 ⊕ ∕ G M⊕ = ρ · V M⊕ = μ⊕ ∕ G

Earth mass (M_⊕, where ⊕ is the standard astronomical symbol for planet Earth) is the unit of mass equal to that of Earth. This value includes the atmosphere but excludes the moon. The current best estimate for Earth mass is M_⊕ = 7024597220000000000♠(5.9722±0.0006)×10²⁴ kg Earth mass is a standard unit of mass in astronomy that is used to indicate the masses of other planets, including rocky terrestrial planets and exoplanets.

The mass of Earth is estimated to be:

which can be expressed in terms of solar mass as:

The ratio of Earth mass to lunar mass has been measured to great accuracy. The current best estimate is:

The mass of Earth is measured indirectly by determining other quantities such as Earth's density, gravity, or gravitational constant.

Modern methods of determining the mass of Earth involve calculating the gravitational coefficient of the Earth and dividing by the Newtonian constant of gravitation,

The GM_⊕ product is determined using laser ranging data from Earth-orbiting satellites. The GM_⊕ product can also be calculated by observing the motion of the Moon or the period of a pendulum at various elevations. These methods are less precise than observations of artificial satellites.

Earlier efforts (after 1798) to determine Earth's mass involved measuring G directly as in the Cavendish experiment. Earth's mass could be then found by combining two equations; Newton's second law, and Newton's law of universal gravitation:

Substituting earth's gravity, g for the acceleration term, and combining the two equations gives

The equation can then be solved for M_⊕