Syzygy (astronomy)

Sysigia (from other Greek: σύ-ζῠγος , “conjugation, conjunction”) is the alignment of three or more astronomical bodies within the solar system on one straight line.

This term is usually used in an astronomical and astrological context. The term is most often used to refer to the position of the Sun , Earth, and Moon during new moons or full moons. Syzygy is called the position of the Moon when its longitude coincides with the longitude of the Sun (at the same time a new moon is observed) or differs from the Sun's longitude by 180 ° (while a full moon is observed). Solar and lunar eclipses occur during syzygies. Especially large tides are associated with syzygies, since in this case the lunar and solar tides are in phase (on the contrary, at the moments of quadrature , when the longitude of the Moon and the Sun differs by 90 °, the amplitude of the tides is minimal, since the lunar tide superimposes on the solar tide, and vice versa).

Although this word is strongly associated with the two phases of the moon, it must be emphasized that the alignment of any three celestial bodies within the solar system (or in any other system of objects located in orbits around the central body) is syzygy. The series does not have to be perfectly even: due to the rare coincidence of the orbital planes for any three bodies in the system, objects located in the syzygy almost never lie on the same line ^[1] .

Mercury passes in front of the Sun, view from Mars (June 3, 2014)

For example, one of such cases occurred on March 21, 1894, at about 11:00 pm GMT, when Mercury passed in front of the Sun (as seen from Venus ), while both of these planets (Mercury and Venus) simultaneously passed in front of the Sun when viewed from Saturn . In June 2014, the Curiosity rover captured Mercury passing in front of the Sun, becoming the first object to observe the transit of planets from a celestial body other than Earth. ^[2]

The word is often used to describe the special position of planets in general. For example, when all the planets are on one side of the Sun, as happened on March 10, 1982 , although they are not necessarily located in a straight line. However, the planetary configuration was more like scattering than a line, and therefore had little to do with syzygy in general, and astronomers do not consider this event to be anything special. The next big “syzygy” is expected on May 19, 2161, when eight planets (excluding Pluto ) are located in the sky within 69 ° from each other, according to the Kitt Peak National Observatory ^[3] .