Moon clouds. The illuminated area of the visible sphere (degree of illumination) is given by formula_3, where formula_4 is the elongation (i.e., the angle between Moon, the observer (on Earth) and the Sun). The gravitational attraction that masses have for one another decreases inversely with the square of the distance of those masses from each other. As a result, the slightly greater attraction that the Moon has for the side of Earth closest to the Moon, as compared to the part of the Earth opposite the Moon, results in tidal forces. Tidal forces affect both the Earth's crust and oceans. The
Partial eclipses on the Moon Partial eclipses on the Moon Partial solar eclipses on the Moon are caused when the Earth passes nearly in front of the Sun, blocking a part of its light. Viewers on Earth will see a penumbral lunar eclipse. During its eclipses, the Earth will be in new phase, completely dark, except for moonshine and sunlight refracted through the earth's atmosphere, visible as a ring of light. Unlike the Earth's which shows slightly darker shadows at 50% obscuration and mostly dark at over 75% obscuration, the Moon's penumbral shadow on the surface shows light yellow at the start and the end