Sun attracts moon twice then Earth then why moon doesn't change its orbit???

Question

I have calculated Gravity of Earth moon and Moon Sun !!I have found that Sun has twice the gravity on moon then earth have it on moon!
Fg (e/m)=2*10^20N and Fg(m/s) = 4*10^20!!!!

Why this?? Help me

Answer 1

I think you made an error in your calculation. I calculate that the Earth's gravity at the Moon is about 41 times stronger than the Sun's gravity at the Moon.

Oops, I made the error. I misplaced a decimal. You are right, the force from the Sun is more than the force from the Earth!

I think Vishal G is on the right track. Without the Earth, the Moon would orbit the sun just as the Earth does now. With the Earth, the Moon is still orbiting the Sun, but at the same time it is kept close to the Earth by the Earth's gravity. Another way to look at it is that the Sun is pulling on the Earth and Moon with about the same acceleration. (Not the same force. Since Earth is heavier it has to be pulled with more force to accelerate by the same amount.) So that there is no net force pulling the Moon away from the Earth. But there is a net force keeping the Moon near the Earth, that of the Earth's gravity.

Think of two rocks dropped at the same time from a high place. Earth's gravity pulls each rock with millions of times more force than the gravity of one rock pulls on the other rock, but the rocks will fall together since they were dropped at the same time and are pulled equally by gravity as they fall.

Or think the space shuttle and space station. Just before they dock, they are close to each other but not touching. They do not tend to get pulled apart by Earth's gravity because they are in the same orbit. They do have some really small gravitational attraction between them and could possible be made to orbit each other, very slowly. Or they could be held together by a string to keep from drifting apart. The string wouldn't have to be very strong since they are both just seemingly drifting weightless in space near each other. Even as they are orbiting Earth at 17,000 miles per hour and being pulled by Earth's gravity quite strongly.

Answer 2

The moon actually does orbit the sun. More specifically, the Earth-moon system orbits the sun just as a planet without a moon would. Although the moon orbits the earth, you can take the observe the foci of its orbit, and examine the foci's orbits with respect to the sun. I believe (I can't remember exactly) that it comes close to the predicted orbit for a planet with the mass of the moon + the Earth. So, the effect of gravity on the moon by the sun is sufficient to ensure that both the moon and Earth maintain their orbit around the Sun.

Answer 3

I can only explain in layman's terms. Mass and gravity are closely related. The Earth and Moon are drawing toward the Sun and due to the influence of the Sun's greater gravity, the Moon is drifting away from the Earth. Without the effects of the Solar Wind, I can postulate that the process would go along quicker.

Answer 4

If you draw the path of the moon as it goes around the earth and the earth goes around the sun, the path of the moon will always be concave and arcing around the sun. In other words, the moon mostly orbits the sun with small pertubations that make it goes around the earth.

Answer 5

that's not likely or the Moon would be pulled away from the Earth in short order...
the Moon is only 225,000 miles from the Earth and 93,000,000 miles from the Sun

Answer 6

Moon's orbit is changing it is very slowly getting further and further away from Earth.

Answer 7

the moon hit the earth 4 billion years ago
it should have been closer to the sun but has been knocked back by such force 4 billion years ago that it stays and orbits there

Answer 8

Recalculate or post the calculation how you arrived at these numbers