Quadrature (astronomy)

The term quadrature in astronomy has two meanings:

• Settings or appearance of a higher planet such that the planet forms with the Sun a 90th angle seen from Earth. There are two, one Eastern square and one Western square. During the squares the planet presents a minimal phase.

• Position of the Moon in the growing and dwindling rooms. In them the Moon forms with the Sun a 90th angle seen from Earth. In this configuration the instant high moon tide matches the low solar tide, being its most important consequence that the smallest high tide occurs.