%0 Journal Article %T The Reciprocity Principle in Gravitational Interactions %A Angel Fierros Palacios %J Open Access Library Journal %V 3 %N 3 %P 1-4 %@ 2333-9721 %D 2016 %I Open Access Library %R 10.4236/oalib.1102412 %X In this paper it is proposed that the ratio between the apparent radius of any two celestial bodies separated by a very big distance, as seemed each other at a distance, is numerically equal to the ratio of the respective real values of their radius. That relationship is what is called in the paper the Reciprocity Principle. In other words, the apparent size of heavenly bodies, as seemed at a distance, plays a special role in the gravitational interactions. This is so because of some kind of effect over the size due to the very big distances in space. When a couple of celestial bodies interact each other, both of them can be considered as sources of the gravity attraction. In that situation, each body acts upon the other in such a way that it can be considered that there are some degree of reciprocal interaction. In this paper, a formal definition of that reciprocal effect is given. %K Escape Velocity %K Apparent Size %K Reciprocity Principle %U http://www.oalib.com/paper/4918373