When we think of outer space, we sometimes assume that there is no gravity because we see astronauts floating around aboard spacecraft such as the International Space Station (ISS). While astronauts do, in fact, experience weightlessness in a zero-gravity environment inside the ISS, the reason is not the complete lack of gravity.
If there were to be no gravity in outer space, all man-made satellites launched to space would escape Earth’s orbit and simply fly off. The moon, the Earth and all the planets would shoot off, making a beeline out of the solar system.
Gravity keeps satellites orbiting Earth
Gravity therefore still exists in outer space – it is what keeps the moon and artificial satellites orbiting Earth; it is what keeps the Earth and all the other planets with their respective moons orbiting the sun and also what keeps the sun and the entire solar system orbiting the centre of our galaxy, the Milky Way.
The reason why astronauts experience zero gravity in the ISS is only because of its high orbital speed. The spacecraft is experiencing freefall all the time due to earth’s gravity, but it is going fast enough to avoid getting any closer to the Earth’s surface, making the ISS in orbit around the Earth.