# Why are tidal forces pointing away from the Moon? [duplicate]

I am currently reading The Science of Insterstellar, which explains most things very well, but some things leave me confuzzled, which I hope to get answers to here. I am no physicist, but highly interested and eager to learn.

I get tidal forces in principle, but one thing never clicked for me, and that is why tidal forces are the reason that the opposite side to the other object (moon, black hole, whatever) point away from said object.

Take this picture from wiki;

https://en.wikipedia.org/wiki/File:Field_tidal.svg

I understand all vectors up to the middle of the circle, where they point inwards and ever so slightly to the right.

Everything left from that is a mystery to me. How can the sum of all the forces pointing towards the object on the right result to vectors pointing away from it?

Even when I remembered that the object itself also has gravity in itself, all those vectors should also point inwards to the object.

How can the vectors (which I understand to be the sum of all gravitational forces ... ?) point away from the mass?

• physics.stackexchange.com/q/121830 Jul 20, 2015 at 8:29
• @dmckee Interesting... But that only means that our tidal waves of the sea level don't exist, right? The forces themselves (as depicted here) are still valid?
– F.P
Jul 20, 2015 at 8:49
• No, it means that the picture the book offered you is highly idealized. Jul 20, 2015 at 9:07