Syzygy

Syzygy (noun): the nearly straight-line configuration of three celestial bodies (as the Sun, Moon and Earth during a solar or lunar eclipse) in a gravitational system.

Syzygy is when three of the bodies in the solar system line up in a row. This term is most often used to refer to a Sun-Moon-Earth lineup. During one of these, the gravitational stress on the moon can cause a Moonquake, the Moon's equivalent of an earthquake. However, it is highly unlikely that a Sun-Moon-Earth syzygy can cause an earthquake, since the Earth is 82 times more massive than the Moon.

This word comes from the Latin syzygia, "conjunction," and the Greek syzygos, "yolked together."

Bibliography

1. Moche, Dinah L. Astronomy: A Self-Teaching Guide. Hoboken, NJ: John Wiley & Sons, Inc., 2009.

2. Wikipedia. "Syzygy (astronomy)." Wikipedia. 31 March 2013. Wikipedia. 21 May 2013. <http://en.wikipedia.org/wiki/Syzygy_(astronomy)>