Physics
Weight vs. Mass: Understanding the Difference
Quick fact
In the International Space Station, astronauts appear weightless because they are in free fall, but their mass is exactly the same as on Earth.
Why this is interesting
You probably think of your weight as a fixed number, but if you stood on a scale on the Moon, you'd weigh only about one-sixth of your Earth weight. Yet your body hasn't changed—so what actually changed?