Final answer:
Astronauts are considered 'weightless' in space because they do not feel the force of gravity while in a free-fall orbit around Earth, even though their mass remains the same.
Weight is a measure of the gravitational force on an object's mass, and this force changes with difference in gravity levels, whereas mass is constant.
Step-by-step explanation:
Astronauts in space are said to be "weightless" because weight depends on the force of gravity acting on an object's mass.
This sense of weightlessness occurs because astronauts are in a state of continuous free-fall around the Earth, thus not feeling the force of gravity in the same way they would on the surface.
However, their mass remains unchanged irrespective of their location in space or the presence of gravity.
For example, an astronaut's mass does not change when they travel to the Moon, but their weight does, because the
Moon's gravity is only one-sixth that of Earth's, causing them to feel lighter.
This concept also applies to the effect of microgravity on astronauts orbiting the Earth, which creates conditions that seem like there is no gravity, but in reality, they are in a free-fall state, accelerating due to Earth's gravity.
The confusion between weight and mass arises from their relationship: weight is the measure of gravity's pull on mass.
When you are losing "weight," you're actually reducing your mass, which leads to a lower force of gravity acting upon you and thus a lower weight measurement.