Mass and weight

Mass is the amount of matter in an object and never changes, whether you're in Lagos or on the moon. Weight, however, is the force of gravity pulling that object downward, so it changes depending on where you are. Think of a bag of rice at your local market—its mass stays constant at, say, 50 kilograms whether it's in Kano or Calabar. But if you could somehow weigh it on the moon, it would feel lighter because the moon's gravity is weaker than Earth's.

Mathematically, weight equals mass times gravitational acceleration, so W = mg. On Earth, g equals 10 N/kg (or 9.8 N/kg more precisely), but on the moon, g is only 1.6 N/kg. This is why astronauts bounce around on the moon despite having the same mass as on Earth.