Gravity in Space: Why is Zero Gravity?

[jobyts]

Why there is zero gravity in space? Shouldn't there always be a resultant gravity in every point in the space from all the stars/planets in the universe?

 

[Shooting Star]

There is. Far from a massive body, it may be very less.

What force do you think makes the Earth go round the Sun or the moon round the earth?

There is zero gravity wrt to a frame in free fall. For example, in the satellites orbiting the earth, we see that effectively there is no gravity. That is because there is no relative force between the objects inside and the satellite (except for very minute tidal forces), because both are moving at the same rate.

Look up a recent thread which explains this in more detail.

 

[tacman]

The concept of zero gravity in space can be a bit confusing as it is often associated with weightlessness and the absence of gravity. However, the truth is that gravity does exist in space, but it is not experienced in the same way as it is on Earth.

The reason for this is because gravity is a force that is dependent on mass and distance. In space, there is a significant distance between objects such as planets and stars, which results in a weaker gravitational force. Additionally, the mass of these objects is spread out over a large area, further reducing the strength of the gravitational pull.

It is also important to note that the concept of zero gravity only applies to objects that are in a state of freefall, such as astronauts in orbit around the Earth. In reality, they are still being pulled towards the Earth by gravity, but they are moving at such a high speed that they continuously fall around the planet, giving the illusion of weightlessness.

Furthermore, the gravitational force of other celestial bodies in the universe does exist, but it is often negligible compared to the forces acting on an object in space. This is because the universe is vast, and the gravitational pull of a distant star or planet is usually very weak when compared to the massive objects in our immediate vicinity.

In conclusion, while there is technically no such thing as zero gravity in space, the weak gravitational forces and the effects of freefall create an environment where the perception of weightlessness exists. So, while there is always a resultant gravity in every point in space, it is often too weak to be noticeable.