I don't understand why the moon could leave its current orbit. sure there always minute fluctuations in its orbit but I think newton was a pretty smart guy.
The Moon has been moving farther away from the Earth, every year since it parked itself around the planet. About 1 inch a year. It is an interesting topic in the orbital mechanics discussions. I think many people forget the Moon is also being tugged at by the Sun, Venus, and Jupiter, as well as Earth. The interaction between those bodies is complex and will vary, depending on alignments. However, the gravitational force between the Sun and the Moon is, approximately (will vary with the Moon's orbital location relative to Earth and the Sun) over twice as large as that of the gravitational force between the Earth and Moon.
During the Moon's near apogee and while in New Moon, and Venus happens to be between Earth and the Sun, the gravitational pull on the Moon, away from Earth, is at its peak. In this position, the Moon also happens to be going the opposite direction of Earth's solar orbit direction exposing the Moon to the Sun/Venus gravitational forces for longer periods of time. This slows the Moon's approach to near perigee. All indications show this particular interaction to be the cause of the Moon's drift away from Earth.
In my spare time (so little of that lately) I had been working on a computer model of this. There are any number of possibilities, at this point in time. Departure of the Moon from Earth's orbit is probable. While I am not an expert on this topic, I find it fascinating and spend a bit of time keeping up on it.
Not to put down Newton, but he would probably struggle in a quality high school physics or trigonometry class today.
