How Does the Earth Hang Out in Space?

Author: Vatika

You may have seen astronauts on the International Space Station (ISS) floating around and drinking blobs of water. Or you may have seen people in Star Wars having battles in space without usually falling into planets or moons. But how does this work? How do objects in space, like the Earth, not fall? How do they float?

The interesting thing is that the Earth and all other celestial bodies (planets, moons, asteroids, etc.), everything in space, aren’t actually floating, they are in fact falling (but we just can’t see it)!¹ Since space is a big, black, void vacuum, there is not enough light for us to see the motion of the objects in space, and they aren’t falling in the traditional sense that we’re used to here down on Earth.²

So, if the Earth is actually falling, why isn’t it hitting anything? This is because of three main reasons.

The first being gravity (the thing that keeps you grounded to the surface of the Earth so you don’t start flying away to space).³ The Earth orbits (circles) the Sun and stays in the orbital revolution due to the gravitational pull the Earth experiences from the Sun. Because the Sun is more massive (heavier) than the Earth, the Earth feels the gravitational pull from the Sun, attracting the Earth towards it.⁴ If the Earth were more massive than the Sun, the Sun would be attracted towards the Earth.⁵ If the two bodies are about the same mass, they would be orbiting each other.⁶

So, if the Earth is attracted to the Sun and the Earth is falling, why aren’t we falling into the Sun and burning up?

This is due to the second and third reasons, being distance and speed.⁷ We are far enough away from the Sun that the gravity acting upon us doesn’t pull us all the way to the sun but it does keep us close enough that we don’t fly off into outer space.⁸ The Earth is falling at just the right speed so that instead of falling completely, it ends up orbiting the Sun.

To better visualize this, it might be helpful to think of it how Isaac Newton did. If you were to shoot a cannon from the tip of the North Pole, it shoots out but eventually falls down. It shoots out at a far enough distance because of the momentum the speed it is shot out with has but it falls down because of the force of gravity on it. It however, doesn’t fall all the way through the Earth because there is an equal and opposite force, called the Normal force acting upon it that prevents that. But what if you were to shoot the cannon at a higher speed? It does shoot out further and may eventually fall. However, if you were to shoot it out at just the right speed, it will overcome the force of gravity and start going in a circle around the surface of the Earth because of the momentum provided by the initial push out of the cannon at the right speed. This is also how the ISS orbits the Earth and how the Earth orbits the Sun. They are going at just the right speed to be able to avoid crashing into their more massive counterpart.

If you have been on a roller coaster, the feeling of free fall after the first drop is what the Earth is constantly in and it is because of its own momentum and speed that it doesn’t fly off one way or another, similar to how the seat belts and restraints on the roller coaster, keep us from flying off.⁹ However, because of the laws of physics, we appear to see things as if they are floating in space.

1.  Fraknoi, Andrew, David Morrison, and Sidney Wolff. “Orbits and Gravity.” In Astronomy 2e. Houston, Texas: OpenStax, 2022. https://openstax.org/books/astronomy-2e/pages/3-thinking-ahead.

2.  Fraknoi, “Orbits and Gravity”.

3.  Fraknoi, “Orbits and Gravity”.

4.  Fraknoi, “Orbits and Gravity”.

5.  Fraknoi, “Orbits and Gravity”.

6.  Fraknoi, “Orbits and Gravity”.

7.  Fraknoi, “Orbits and Gravity”.

8.  Fraknoi, “Orbits and Gravity”.

9. "Why Do We Float in Space?" MacMillanSpaceCentre. December 17, 2009. Video, https://www.youtube.com/watch?v=4w8WH5-qOcU&ab_channel=MacMillanSpaceCentre.