Is mass a constant on Earth?
Your mass is constant no matter where you are in the universe. Your weight however, is dependent upon how strong a gravitational field you are in. Think of it this way, imagine Neil Armstrong in 2 situations, one on Earth and the other on the Moon. He is made up of the same physical stuff in both situations, so his mass is the same, but because the moon has less gravity, he has less weight than on Earth.
