Earth masses
| Earth Mass | |
|---|---|
| Unit system | astronomy |
| Unit of | mass |
| Symbol | M⊕ |
| Unit conversions | |
| 1 M⊕ in ... | ... is equal to ... |
| SI base unit | (5.9722±0.0006)×1024 kg |
| U.S. customary | ≈ 1.3166×1025 pounds |
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⊕ = (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 for the Earth is called the geocentric gravitational constant and equals 398600.4418±0.0008 km3 s−2. It is determined using laser ranging data from Earth-orbiting satellites, such as LAGEOS-1. 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.
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