How is it that the moon can affect the 352 quintillion gallons of water in the ocean, but not affect us?


The moon depending on where it is at your time of day can affect whether or not there’s high or low tides. Basically moving all of the water in the ocean, at least that’s how I think. But how come it doesn’t make us feel lighter or heavier throughout the day? Or just seem to affect anything else

In: 407

It does effect us, just very, very minorly. Gravity tends to be more noticeable on objects with a lot of mass. The ocean, being both very very massive along with fluidity, makes gravity very noticeable on it.

When the moon is directly above you as opposed to directly under, you will weigh a very very marginally lighter.

Because gravitational attraction is a function of BOTH masses.

F = gMm / r^2

So if you have tow really big masses, like the moon and the worlds oceans, there’s a lot of force there.

But if you have one big and one little mass, then you have significantly less force.


So instead of thinking the whole ocean is being pulled by the moon, Think of it instead that there is always a bulge of water facing the moon, There is also another bulge of water facing the opposite side of the earth too.

We will call these bulges ‘high tide’.

The earth is actually spinning *through* these bulges of water and as we reach a bulge the ocean gets this extra bulge of water and we experience a high tide.

Once we spin out of the bulge past the moon the water drops again and we experience no bulge which is ‘low tide’.

The rhythm of us passing through these bulges of water each day is the tides.

The bulge is always there being pulled up towards the moon, We just slide through it.

You also get extra bulges from the sun, but these are usually smaller.

[Here is a helpful NASA visualisation](,are%20where%20low%20tides%20occur.)

We’re too small. It does affect us, but to no noticeable degree.

Earth is close to us. It pulls very *heavily* on everything on it. Including all the water on it. This creates a LOT of pressure as the weight of water piles onto itself in the deepest parts of the sea.

The moon pulls *very slightly* on everything on earth. The further it is from us, the less it pulls. So, if the moon is close, everything on earth isn’t being pulled as heavily from the Earth’s gravity, since a *tiny* bit of that force is alleviated.

We can’t notice that change. But, in the deepest parts of the ocean, a *little* bit of change in force is enough to alleviate some of the pressure built up from the water on top of it. On the other side of the planet, water is still being pulled by the moon, compressing it down, creating pressure which will be alleviated when the orbit swings back around.

All the pressure differences across the planet end up creating low and high tides, which as others have described, can be thought of as a “bulge” of water that faces the moon.