What is the difference between mass and weight? Mass is the
measure of how much 'stuff' something has in it. The more 'stuff'
something has, the more mass it has.
Weight, however, is a measure of how much something is pushing
on something else.. The difference between the two is often confused
here on Earth because we tend to equate them since we measure mass and
weight the same way. We measure weight by placing something on a scale.
The scale tells us how much the object pushing against it. Since the
Earth's gravity pulls on each little piece of mass the same, the mass
is easy to figure out from the weight. For instance, if one rock on a
scale weighs 5 pounds, and another weighs 10 pounds, we know that the
second rock had twice as much mass, there was twice as much 'stuff'
there, because it had twice as much force (weight) pushing against the
However in space, we do not feel gravity like we do on Earth. If
an astronaut touches a scale in space, the astronaut will have no
weight because there is no force pushing the astronaut against the
scale. But the astronaut is still made of stuff, so the astronaut still
So the difference between mass and weight, in space or anywhere,
is that mass is the amount of 'stuff' something has, and weight is how
much something pushes against something else.
I hope this answers your question.
(published on 10/22/2007)