Today’s Wonder of the Day was inspired by Alvin. Alvin Wonders, “Why is there no gravity in space?” Thanks for WONDERing with us, Alvin!
Scientists will tell you that the laws of physics do indeed apply in outer space, and it's not a lack of air that accounts for the absence of gravity. So what's going on here? Why isn't there any gravity in space?
Those same scientists would actually be quick to correct your misunderstanding. Gravity is everywhere…even in space! So what accounts for that weightless feeling that astronauts experience in outer space? There are a couple of factors that explain it.
Anything with mass creates gravity. The gravity generated by the Sun, Earth, the Moon, and other planets stretches throughout outer space. However, the effect of that gravity decreases as distance increases. At extreme distances, the gravity exerted on a particular object might be almost zero, but it will never be completely absent.
Distance alone doesn't account for the weightless feeling astronauts get, however. To feel like there is no gravity due to distance, the distance must be truly extreme. For example, at the orbit of the International Space Station, which is approximately 250 miles above Earth, Earth's gravitational pull is still about 90% of what it is at Earth's surface.
The weightless feeling astronauts experience can be explained by their relation to the spaceship they're on. Astronauts on spaceships in outer space are affected by gravity in the same way that their spaceships are. They are both orbiting Earth, which means they're falling sideways at the same time they're falling toward Earth.
On Earth, astronauts feel the force of gravity as weight, because Earth's surface prevents them from falling. In outer space, however, there is no ground to push against astronauts. As they orbit and fall toward Earth at the same rate as their spaceship, astronauts feel weightless, as if there were no gravity.
Gravity exists everywhere, even in outer space. It may be so small at great distances that it's almost undetectable. Closer to Earth, however, astronauts get that weightless feeling not because of the absence of gravity, but because they're falling at the same rate as their spaceship and there's no ground to stop their fall and create the sensation of weight.