Quadrature

noun

1. The process of making something square; squaring.
2. The act or process of constructing a square that has the same area as a given plane figure, or of computing that area.
3. (numerical analysis) The calculation of a definite integral by numerical means.
4. The act or process of solving an indefinite integral by symbolic means.
5. A situation in which the directions of two celestial bodies (or a celestial body and the Sun) form a right-angle from the perspective of the observer.

   "When the Moon is in quadrature, it appears in the sky as a half-moon."