Syzygy
A syzygy is an alignment of three celestial bodies in a straight line — most familiarly the Sun, Earth and Moon during an eclipse.
Full definition of Syzygy →:: COMPARE ::
SyzygyvsConjunction
The short answer
A conjunction is an apparent close approach of two bodies on the sky as seen from a third; a syzygy is a genuine near-straight-line alignment of three. Conjunction is about appearance, syzygy about actual geometry — two objects can look adjacent without being lined up at all.
Side by side
| Aspect | Syzygy | Conjunction |
|---|---|---|
| Bodies | Three | Two, plus observer |
| About | Real geometry | Apparent position |
| Produces | Eclipses, tides | A close pairing |
| Requires alignment | Yes | No |
What each one means
Conjunction
The contrast above sets out how Conjunction differs from Syzygy on the points that actually matter.