Syzygy (astronomy)

In astronomy, a syzygy (/ˈsɪzədʒi/ SIZ-ə-jee; from Ancient Greek συζυγία (suzugía) 'union, yoke')^[1] is a roughly straight-line configuration of three or more celestial bodies in a gravitational system.^[2]

The word is often used in reference to the Sun, Earth, and either the Moon or a planet, where the latter is in conjunction or opposition. Solar and lunar eclipses occur at times of syzygy, as do transits and occultations. The term is often applied when the Sun and Moon are in conjunction (new moon) or opposition (full moon).^[3]

When Earth is one of the bodies involved, the other objects appear to be close together (or overlapping) in the sky.