# Gravitation in the solar system

• Neohaven
In summary: I'll go back and correct it.In summary, if the moon were to explode, it would cause changes in the Earth's orbit, water levels, and rotational speed, but these changes would happen gradually and not suddenly. The moon's gravitational pull is currently causing Earth's rotation to slow down very slowly, but if the moon were to suddenly disappear, there would be no immediate effect on Earth's rotation.
Neohaven
Let's say, in an hypothetic situation, that the moon would explode to tiny bits.

What would happen to the earth?

I was said it would actually change:

The orbit of the Earth *duh!*
Water levels all around the world *duh!*

And the point I have a problem with is this last one...

It will change the Earth's rotational speed, this derived from the fact that the moon goes around the Earth at the same speed than the Earth revolves upon it's own axis... Is this true, or totally fallacious?

The person in question also mentioned studies regarding this possible fallacy...

First we have the sun-exploding thread. Now we have the moon-exploding thread. What's with all this all of the sudden? Is someone running a crackpot website and posting all of these questions, while you guys bite the bait?

Zz.

"...the moon goes around the Earth at the same speed than the Earth revolves upon it's own axis..."

Think about this for a second. If the Moon overhead were orbiting at the same speed as the Earth rotates below, then the Moon would always hover over the same spot on Earth.

Does it? No. The Moon is in a different place overhead (and sometimes not at all) every day.

You should tell your friend to shut up until he knows what he's talking about.

DaveC426913 said:
"...the moon goes around the Earth at the same speed than the Earth revolves upon it's own axis..."

Think about this for a second. If the Moon overhead were orbiting at the same speed as the Earth rotates below, then the Moon would always hover over the same spot on Earth.

Does it? No. The Moon is in a different place overhead (and sometimes not at all) every day.

You should tell your friend to shut up until he knows what he's talking about.

*chuckle* Aye, that was about what I was going to tell him. hehe

Hold on, doesn't the Moon affect the Earth's rotation rate anyway?
Isn't it slowing down as the Moon moves further away from us?
(Fossils show the Earth's day was much shorter in prehistoric times when the Moon was closer.)

Earth's rotation rate, and Moon's orbit are gradually synchronising.
It's called 'tidal locking'
The Moon is already tidally locked to the Earth (we always see the same face of the Moon, all but a slight rocking - called 'libration')

I suppose if the Moon were suddenly vapourised, then the Earth's rotation would stop slowing.

But it ain't going to happen...

So the moon DOES affect the Earth's rotational speed?

Neohaven said:
So the moon DOES affect the Earth's rotational speed?

Yes, it slows it down very slowly, but if you remove the moon, the rotation speed will not suddenly change, it will just stop slowing down.

Just for perspective; the Moon's gravitational "drag" slows the Earth's rotation by about 1.5 milliseconds per century. it takes a hundred million years for the Earth's "day" to get a second-and-a-half longer. If this deceleration were to cease, then a hundred million years from now a day will be just as long as it is today, rather than 1.5 seconds longer.

We live with this deceleration every day of our lives. However, if it were to suddenly dissapear, I don't think anyone would fall over! Of course, here in Michigan, we just moved our clocks back one hour yesterday (Sunday); I wonder if that would get messed up?

If the moon exploded, by conservation of momentum, the center of mass of the moon would remain in the same place. So there would be no net effect

:P

(For a little while at any rate...)

Well, if the Earth rotation slows down for about 1.5 milliseconds(1.5x10^-3 sec; per day) in one century it would take 100.000 years(1000 centuries) until the day would be 1.5 seconds longer.

Ooops! You're absolutely right, sstone. I missplaced my decimal, did microseconds instead of milliseconds; one hundred thousand years is the correct figure not one hundred million.

Thanks for catching that.

## 1. What is gravitation in the solar system?

Gravitation in the solar system is the force of attraction between all objects with mass in the solar system. It is responsible for keeping planets in orbit around the sun, as well as the moon in orbit around Earth.

## 2. How does gravitation affect the motion of objects in the solar system?

Gravitation affects the motion of objects in the solar system by pulling them towards each other. This force is responsible for keeping planets in their orbits and can also cause objects to collide or be pulled into each other.

## 3. What is the role of the sun in gravitation?

The sun plays a critical role in gravitation in the solar system. It is the largest and most massive object, and therefore has the strongest gravitational pull. This pull keeps all the planets in their orbits and is also responsible for the formation and stability of the solar system.

## 4. How does the distance between objects affect gravitation in the solar system?

The strength of gravitation between two objects is directly proportional to their masses and inversely proportional to the square of the distance between them. This means that the closer two objects are, the stronger the gravitational force between them.

## 5. Can gravitation in the solar system be affected by other factors?

Yes, other factors such as the mass and distance of nearby objects, as well as the effects of general relativity, can influence gravitation in the solar system. However, the overall force of gravitation is still the dominant force that shapes the motion and structure of the solar system.

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