# why do things weigh less on the moon

Weight, mass and gravity
People often confuse mass and weight. Remember that weight is a force, and is measured in newtons. Mass is measured in kilograms (kg). The mass of an object is the amount of matter or \”stuff\” it contains. The more matter an object contains, the greater its mass. An elephant contains more matter than a mouse, so it has a greater mass. Mass is measured in kilograms, kg, or grams, g. A 100 kg object has a greater mass than a 5 kg object. Remember an object\’s mass stays the same wherever it is. All objects have a force that attracts them towards each other. This is called gravity. Even you attract other objects to you because of gravity, but you have too little mass for the force to be very strong. Gravity only becomes noticeable when there is a really massive object like a moon, planet or star. We are pulled down towards the ground because of gravity. The gravitational force pulls in the direction towards the centre of the Earth.

Weight is a force caused by gravity. The weight of an object is the gravitational force between the object and the Earth. The more mass the object has the greater its weight will be. Weight is a force, so it\’s measured in newtons. On the surface of the Earth an object with a mass of 1 kg has a weight of about 10 N. The mass of an object stays the same wherever it is, but its weight can change. This happens if the object goes somewhere where gravity is stronger, or weaker, such as the Moon. The Moon has less mass than the Earth, so its gravity is less than the Earth\’s gravity. This means that objects weigh less on the Moon than they do on the Earth. The Moon\’s gravity is one sixth of the Earth\’s gravity. A 120 kg astronaut weighs 1200 N on Earth. On the Moon they would weigh only 200 N. The astronaut\’s mass is 120kg wherever they are. Actually. Your mass is equal everywhere in the universe, since mass is a measure of the amount of stuff that something is made out of.

The force of gravity pulling on said mass (aka, the weight) is different depending on the amount of gravity on whatever thing you re weighing said mass on. To go further, if it has mass, it has gravity, and it will pull on other things with a mass. Which means that you pull on the earth as it pulls you–but the pull of the earth overwhelms the indescribably small amount of gravity you have in comparison, so you fall towards earth, rather than the earth falling towards you. (Though arguably, you and the earth are falling towards each other to some tiny fraction of a degree). If you happened to have a small marble with you while you were light years from the nearest object (assuming you could just get to said spot) and you let go of the marble at an arm s length away from you, you will see the marble come towards you again, because your body s gravity will pull it in.

The more mass something has, the more gravity it is said to have, but something does not have less mass because it weighs less. Something has less mass because it lost it somehow. Hence the law of conservation of matter. Edit: wait, do you mean that the moon has less mass? Or that the object you re weighing has less mass. I re-read your thought and can t decide which you meant, but I originally read it as if the object you re weighing has less mass because it weighs less on the moon. If you meant that the moon has less mass therefore you can figure out the weight of a planet by sending a known, earth-measured weight on a kitchen scale, to another planet, weighing that object there on the same scale you used on earth, then yes, you could calculate the mass of the planet needed to cause a gravitational pull to make the earth-measured weight whatever it is on the new planet.

You can then hypothetically take the mass of the planet, and figure out what it would theoretically weigh here on earth. I would challenge you to worry about the amount of stuff a certain thing has (whether it s a planet or a grain of sand) rather than weight, because weight, with respect to the simple properties of matter, isn t relevant anywhere there isn t uniform gravity, which is arguably not in this universe. Weight is relevant only in our universe as an effect of matter being near other matter and how much matter is near each other In general. Thought experiment: if you could picture the entire universe in your head, and like a heat map, light up all the areas with strong gravity, and dim the areas with weak gravity, you d see that weight would just be irrelevant in the universe since weight is not universal (no pun intended) BUT what is universal (pun intended) is the amount of matter an object has.