Gravity is what keeps our feet firmly planted on the Earth and maintains the Earth’s stable orbit around the sun. You’ve probably heard that there’s no gravity in space, but that’s just not true. In reality, gravity is everywhere in space and has an infinite reach.
This can be understood through Newton’s law of universal gravitation. The “r” in the denominator of Newton’s equation represents the distance between objects. No matter how large this number gets, gravity is still present. It becomes weaker the farther you are from massive objects but never reaches zero. This means the sun exerts a non-zero gravitational effect across the universe, and so does the Earth. While this force gets extremely weak the further away you go, it never completely disappears.
Newton’s equation also reveals that close to massive objects like the Earth, gravity is quite strong. You might be surprised to learn that the force of gravity on the International Space Station, which orbits about 250 miles or 400 kilometers away in space, is almost the same as on the surface of the Earth.
