Syzygy (astronomy)
Syzygy (also Syzygium , plural syzygies , Greek - Latin 'joining', from Greek syzygia 'team') describes a constellation in astronomy in which the sun on the one hand and the moon or one of the planets on the other are at the same geocentric ecliptical length stand. In a heliocentric view, the sun z. B. Earth, which then has the same heliocentric ecliptical length as the Earth's moon or one of the planets.
Syzygy is a collective term for opposition and conjunction .
The three celestial bodies brought into relation are generally not exactly on a common line in space (because of slight deviations from the ecliptic plane ), but in a common plane that is perpendicular to the ecliptic plane. The intersection of both levels is called the syzygy line .
If the moon is on the ecliptic plane (center points of earth, moon and sun on a common line), the best positions for a solar eclipse or a lunar eclipse are available. In these cases the moon just passes the nodal line , i.e. the line of intersection between the plane of the moon's orbit and the ecliptic plane, which in this position corresponds to the syzygy line.
literature
- Arnold Hanslmeier : Introduction to Astronomy and Astrophysics , Spectrum Academic Publishing House, 2nd edition 2007. ISBN 978-3-8274-1846-3