Depending on how you define weight, standing on the moon’s surface changes some aspects of weight, but not others. Your scale weight would be less due to the moon’s lighter gravity, but your body mass would not change.
Your Mass
Your body mass -- the amount of matter it takes to make you -- doesn’t change regardless of whether you are standing on the moon, the Earth, or weightless in the space capsule taking you from the Earth to the moon. Unless you actually lose or gain mass on the trip, your mass will not change regardless of the numbers shown on the scale. In this manner, your “weight” doesn’t change, because you still have the same mass.
Gravity and Scale Weight
Gravity exerts a pull on your body’s mass toward the core of the moon when you are standing on the moon. The gravitational force determines how much a scale shows you weigh. The moon’s gravitational force is approximately one-sixth that of the Earth’s, so your weight on the moon would be roughly one-sixth of what you weigh on the earth, according to NASA’s “Computing Human Weight on the Moon” article. This is the simplest method to determine your weight on the moon, but it does not indicate the most precise method. More precisely, your weight on the moon is 16.5 percent of your weight on the Earth, according to the Learning About Electronics website.
Newton’s Universal Gravitation Law
Sir Isaac Newton discovered that gravity was universal. The mass of any two objects exerts a pull on one another. Therefore, when you are standing on the moon, your mass responds to the gravitational pull of the moon, and when you are standing on the Earth -- or any other planet -- your mass responds to the gravitation pull of that planet. The planetary body with the greater mass will exert the most pull; therefore, the scale will show a larger weight number on the larger body. Since Jupiter is much larger than either the moon or the Earth, the same scale there would show a heavier number than your weight on either of the smaller bodies.
How Microgravity Affects Your Mass
If you remained on the moon or took a long journey in space, over time your muscles would deteriorate, because there would not be sufficient gravity to push against, according to NASA’s article, "Gravity Hurts (So Good).” In the zero gravity of space, you have no gravity to push against, so muscles atrophy quickly and you lose bone. Your muscles and bone would last longer in the microgravity of the moon, but unless you compensate with resistance exercises that help counter the effects of lower gravity, you will lose mass, and thus weight, on the moon.
