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Zero Gravity, Does It Exist?

Is there such a thing as zero gravity?

three astronauts waiting to go into space

Photo: Amy the Nurse (Flickr)

Would you ever want to be an astronaut?

This Moment of Science: Is there such a thing a zero gravity?

No Zero Gravity

Contrary to popular belief, there’s no such thing as zero gravity. Weightlessness and zero gravity are two different things. The earth’s gravity keeps the moon in orbit. And astronauts are generally much closer to earth than the moon is, which means that the earth’s pull on them has to be much stronger.

While we’re on Earth, we feel our weight because, as the Earth’s gravity pulls us into its center, the ground pushes back against our feet.

When astronauts orbit the earth, they’re still subject to gravity, but they’re moving sideways so quickly that even though they’re being pulled towards the earth, they’re not getting any closer to the center of the planet. In other words, they’re basically in a state of constant free fall, and that’s why they’re weightless.

Weaker Gravity

Keep in mind that gravity never disappears entirely. It just gets weaker. And every object with mass, including you and me, has what’s known as gravitational attraction. Although you’re subject to all those forces, the Earth’s gravity masks their pull because the Earth is so large and so close.

So moving away won’t free you of the Earth’s gravity. All that would happen is that the Earth’s pull would be masked by the pull of some other object, like Mars.

  • Sue Wreck

    Interesting article.

  • Zerogravityman

    why you are telling such bull?  Of course zero-gravity exists, somewhere in space.

    Far away from any object in space the gravity can get so weak, that there is close no gravity. Not perfectly zero, but maybe 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001 or less, which is getting pretty close to zero.

  • Ebi

    close to zero is not zero! there is no zero-gravity anywhere. It’s not the gravity forces that cancel each other between moon and the earth. It’s moon’s centrifugal force due to it orbiting earth which cancel’s the earth’s gravitational force.

  • Patrick Clark

    Zero gravity doesn’t exist because there is always something with gravity in our universe, if far, or near, the gravity of those objects has an affect on us. The sun is millions of miles from pluto and still has a gravitational affect on it.

  • Bryan Jensen

    Gravity equals zero at the center of a mass i.e. a planet. Compress a planet to a Plank point and eventually there will be an equal and opposite reaction from a spherical standpoint where x, y, z collide. Guess it would sort of be like the cat at this point both dead and alive, or the acceleration to center has to stop at some point to accelerate away from center. Run into a wall at some time there is a point of no movement between you and the wall. Granted the mass is still moving through a spacetime but for the necessary calculations you can show the acceleration of gravity equal to zero.

  • Socrates

    Since I can assume there is a relative gravity for anywhere in the universe, then may I assume that zero gravity can never exist? The big bang, solar systems and galaxies are being spread out in the universe, hence the universe constantly expanding…since everything is expanding STILL and everything is attracted to one another through gravity, then no where in space there is Zero Gravity?

    That being said however, astronauts will experience gravity extremely close to zero but since the universe keeps expanding and everything attracts one another, then there is no ABSOLUTE zero, just a rounded down zero?

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