Earth-Moon Center of Gravity Name: David C. where is the center
of gravity for the earth-moon system, what effect does this have
on the orbit of the earth around the sun? The center of gravity
of the earth-moon system is inside the earth on the line between
the centers of the two bodies. This center of mass proceeds
around the sun in an elliptical orbit. Richard E. Barrans Jr.,
Ph.D. PG Research Foundation, Darien, Illinois These web sites
offer some insight into what appears to be a simple question. In
the crudest approximately the center of gravity of the
moon/earth system is about 2900 km or about 75% of the radius
from the center of the earth. However, things are much more
complex than that. The sun cannot be neglected; in fact it has a
large effect on tides. So it is the sun/moon/earth system that
must be taken into account. In addition, there are at least 10
more drags, wobbles, various wiggles caused by many sources
including the planets, the tidal drag of the oceans, and the
fact that the center of ea