So here you have two definitions of a blue moon but the one for a calendar blue moon does not describe the true meaning of a blue moon. Here's why:
A billion years ago, our Moon was closer to Earth than it is now. As a result, it appeared to be a much larger object in the sky. During that ancient era, if human beings had been around to witness such a sight, it would have been possible to see the entire Moon--not merely the one near side face that we see now. A billion years ago, it took our Moon only twenty days to orbit our planet, and Earth's own day was considerably shorter--only eighteen hours long. Stupendous, almost unimaginably enormous tides, that were more than a kilometer in height, would ebb and flow every few hours. However, things changed, as the lunar orbit around our primordial planet grew ever wider and wider. Annually, Earth's Moon moves about 1.6 inches farther out into space. Currently, the lunar rate of rotation, as well as the time it takes to circle our planet, are the same.
Saturn is the smaller of the two gas-giant planets, twirling around our Sun, in the outer regions of our Solar System--far from the delightful warmth of our lovely incandescent roiling gas-ball of a Star. Jupiter is the larger of the duo of gas-giants dwelling in our Solar System, as well as the largest planet in our Sun's bewitching family, which is composed of eight major planets, an assortment of moons and moonlets, and a rich menagerie of smaller objects. Saturn is the second-largest planet in our Solar System--and probably the most beautiful.