If astronauts are floating in the International Space Station, seemingly weightless, does that mean there’s absolutely no gravity acting on them? Or is it more nuanced than that? Could there be gravity present, but something else is causing them to float? If gravity is present, how strong is it compared to Earth’s gravity at the surface? And if there is a tiny amount of gravity, why don’t the astronauts simply fall back down to Earth?

Answer

No, there is gravity in space. Gravity is a fundamental force of attraction between any two objects with mass. The amount of gravity depends on the masses of the objects and the distance between them.

Even in the vast expanse of space, gravity is present. The misconception that there is no gravity in space often stems from the experience of astronauts on the International Space Station (ISS) appearing weightless. This apparent weightlessness is not due to the absence of gravity, but rather to the state of freefall.

The ISS is constantly falling towards Earth, but it is also moving forward at a very high speed (about 17,500 miles per hour). This forward motion keeps the ISS orbiting Earth instead of crashing into it. The astronauts inside the ISS are also falling towards Earth at the same rate as the station, which creates the sensation of weightlessness. It is similar to being in an elevator that is falling freely – you would feel weightless because you are falling at the same rate as the elevator.

The Earth’s gravity extends far beyond the Earth’s surface. It keeps the Moon in orbit, and it also affects the motion of satellites and spacecraft. The Sun’s gravity is even more powerful, and it keeps all the planets in our solar system orbiting around it.

Even in interstellar space, far from any stars or planets, gravity is still present. Although it is extremely weak, it can still have an effect on the motion of dust and gas clouds, and it can even bend the path of light.

In summary, gravity is everywhere in space, but its effects can vary depending on the mass and distance of the objects involved. The experience of weightlessness in space is due to freefall, not the absence of gravity.