Weightlessness in Space

Weightlessness is the condition where a person or object experiences no sensation of weight. It is also called zero gravity (zero-g) or zero apparent weight. In reality, gravity is never completely absent, so the term microgravity is often used to describe environments where the effects of gravity are extremely small.

Weight is the force that acts on an object due to gravity. On Earth, this force is felt because objects rest on surfaces like the ground, chairs, or beds. However, in certain conditions, this sensation disappears, leading to weightlessness.

Weightlessness in Space vs. on Earth:

• On Earth: Objects rest on a surface, and the force of gravity creates the sensation of weight.
• In space: Objects are in free fall, and since everything moves at the same rate, there is no sensation of weight.

Astronauts inside a spacecraft appear to float, but this is not because gravity is absent. In fact, even at the height of the International Space Station (ISS), gravity is about 89% as strong as it is on Earth's surface. The reason astronauts feel weightless is that they are in a state of free fall.

A spacecraft in orbit is constantly falling toward the Earth due to gravity. However, it is also moving forward at a very high speed. Because of this forward motion, it never actually reaches the Earth—it keeps missing it and continues moving in a circular path around the planet. This continuous free fall creates the sensation of weightlessness.

Since both the spacecraft and everything inside it (astronauts and objects) are falling at the same rate, they do not press against any surface. If an astronaut lets go of an object, it will not move relative to them, appearing to float.