Weight and Mass

Centre of Mass

Earth and Moon taken by
the Galileo Spacecraft
Credit: NASA
Mass is the amount of "stuff", or matter, and object has and this amount remains the same wherever the object is, even though it's weight will change depending upon gravity.

Mass

Weighing the Earth?

The Weight of something tells us how heavy it is, but the Mass is the amount of "stuff", or matter, and object has and this amount remains the same wherever the object is, even though it's weight will change depending upon gravity. This means even though our mass is the same - our weight varies depending on which planet we are stood on in the solar system!