syzygy

/ˈsɪzɪdʒi/
noun
  1. A straight-line configuration of three celestial bodies (such as the sun, Earth, and moon).
    • Ancient astronomers carefully tracked syzygies to predict eclipses.
    • The spring tides are higher than usual because of the syzygy.
    • A solar eclipse occurs during a syzygy of the sun, moon, and Earth.
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