Weight on Earth and Elsewhere

g Changes Depending on the Celestial Body

The strength of gravity g depends on the celestial body one is on: the more massive a celestial body is, the greater g is, and the more strongly objects are attracted to it.

Celestial Body	g (N/kg)
Earth	10
Moon	1.6
Mars	3.7
Jupiter	25

Same Mass, Different Weight

Take an astronaut with a mass m = 60 kg. Their weight changes depending on where they are, while their mass stays 60 kg everywhere:

• On Earth: P = 60 x 10 = 600 N
• On the Moon: P = 60 x 1.6 = 96 N
• On Mars: P = 60 x 3.7 = 222 N

This is why astronauts jump easily on the Moon: their weight there is much lower, even though their mass has not changed.

What About in Space?

Far from any planet, in weightlessness, g is nearly zero: the weight of an object becomes almost zero, but its mass always stays the same.

Common Pitfall

Never say that an astronaut "no longer has mass" in space. They no longer have weight (or very little), but their mass does not change at all: it is a quantity of matter, independent of gravity.