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An Earth mass (denoted as M 🜨, M ♁ or M E, where 🜨 and ♁ are the astronomical symbols for Earth), is a unit of mass equal to the mass of the planet Earth. The current best estimate for the mass of Earth is M 🜨 = 5.9722 × 10 24 kg , with a relative uncertainty of 10 −4 . [ 2 ]
These proportionalities may be expressed by the formula: where g is the surface gravity of an object, expressed as a multiple of the Earth's, m is its mass, expressed as a multiple of the Earth's mass (5.976 × 10 24 kg) and r its radius, expressed as a multiple of the Earth's (mean) radius (6,371 km). [9]
The solar mass (M ☉), 1.988 92 × 10 30 kg, is a standard way to express mass in astronomy, used to describe the masses of other stars and galaxies. It is equal to the mass of the Sun, about 333 000 times the mass of the Earth or 1 048 times the mass of Jupiter.
The radii of these objects range over three orders of magnitude, from planetary-mass objects like dwarf planets and some moons to the planets and the Sun. This list does not include small Solar System bodies , but it does include a sample of possible planetary-mass objects whose shapes have yet to be determined.
4.5 billion years ago, Earth experienced a cataclysmic rendezvous with a planet named Theia. Evidence of the impact is still buried deep within the Earth.
The choice of solar mass, M ☉, as the basic unit for planetary mass comes directly from the calculations used to determine planetary mass.In the most precise case, that of the Earth itself, the mass is known in terms of solar masses to twelve significant figures: the same mass, in terms of kilograms or other Earth-based units, is only known to five significant figures, which is less than a ...
The standard gravitational parameter μ of a celestial body is the product of the gravitational constant G and the mass M of that body. For two bodies, the parameter may be expressed as G ( m 1 + m 2 ) , or as GM when one body is much larger than the other: μ = G ( M + m ) ≈ G M . {\displaystyle \mu =G(M+m)\approx GM.}
NASA explains, "As stars like our sun age, they puff up into red giants and then gradually lose about half their mass, shrinking down to 1/100th of their original size to roughly the size of Earth ...