Re: Does the earth act as a gravity shield for the moon

Karl,
According to the currently accepted best theory of gravitation, Albert Einstein's General Theory of Relativity, there is no gravitational shielding. Gravitational shielding is also absent from Isaac Newton's classical theory of gravity. Astronomers performing solar system calculations would use one of these two theories and would therefore not include gravitational shielding.

The concept of gravitational shielding was introduced by Italian physicist Quirino Majorana in the publication, Journal de Physique et le Radium. The citation is Q. Majorana, J. Phys. Radium 1, 314 (1930).

In order to continue to be accepted, the General Theory of Relativity must repeatedly survive experimental challenges. Scientists look for anomalies, differences between theoretical predictions and actual experimental results, during eclipses.

A recent (2001) paper by C.S. Unnikrishnan et al. PhysRevD.63.062002 is titled "Anomalous Gravity Data During the 1997 Total Solar Eclipse Do Not Support the Hypothesis of Gravitational Shielding".

So far, it appears that no evidence for gravitational shielding exists. Thus, if you stand on the opposite side of the earth to the moon you will indeed experience the pull of gravity from both the earth and the moon.

[Indeed, this is one way of explaining tides. Moderator]

--Dr. Randall J. Scalise
http://www.phys.psu.edu/~scalise/