Units for measuring masses

The unit of mass in the International System of Units (SI) is the kilogram.
When talking of planets, even exoplanets, masses are measured in masses of the Earth, of Jupiter or of the Sun.
M(Earth) = 6x10²⁴ kg
M(Jupiter) = 2x10²⁷ kg
M(Sun) = 2x10³⁰ kg
Important : mass and weight are not the same thing even if, on the surface of the Earth, it is hard to see the difference! The weight is equal to the mass multiplied by “g”, a value which is (almost) constant on the surface of the Earth. Weight is related to the force of gravity. Mass measures the quantity of matter, which depends solely on the number of atoms and the mass of these atoms.
On Earth, your weight is the attraction between your mass and the mass of the Earth (see [Gravity-art323]) at a distance equal to the radius of the Earth. In interplanetary space, you will not have any weight (weightlessness), but you will still have the same mass. On the surface of the Moon, your weight will be one sixth of what it would be on Earth.