Do you know what is the difference between the principles of mass and weight? While the mass (kilograms) of an object is directly related to how much matter this object has, its weight (newtons) is associated to how strongly gravity pulls on it. So while the mass of something will remain the same whether it’s on earth or another planet, its weight will change depending on the gravitational pull of the celestial body its sitting on. Here’s a short video from Eureka, a series I used to particularly like when I was a kid, explaining both concepts.