Of moons and planets

Something fascinating from an “amateur analysis” of the moon’s orbit — the sort of thing I’m sure a lot of people wish they did but never do.

The Moon’s orbit around the earth

In other words, the Sun exerts more than twice as much gravitational force on the Moon as the Earth does. Asimov argued that this means the Moon is really orbiting the Sun, with some perturbation by the Earth, and that’s why the Moon’s path looks like a slightly wobbly circle around the Sun.

We might look upon the Moon, then, as neither a true satellite of the Earth, nor captured one, but as a planet, in its own right, moving about the Sun, in careful step with the Earth. To be sure, from within the Earth-Moon system, the simplest way of picturing the situation is to have the Moon revolve about the Earth; but if you were to draw a picture of the orbits of the Earth and Moon about the Sun, exactly to scale, you would see that the Moon’s orbit is everywhere concave toward the Sun. It is always “falling” toward the Sun.

P.S. the link to the Asimov book is here.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s