Editing Conjunction (astronomy) (section)

==Multiple conjunctions and quasiconjunctions==
Conjunctions between two planets can be single, [[triple conjunction|triple]], or even quintuple. Quintuple conjunctions involve Mercury, because it moves rapidly east and west of the sun, in a [[synodic cycle]] just 116 days in length. An example will occur in 2048, when Venus, moving eastward behind the Sun, encounters Mercury five times (February 16, March 16, May 27, August 13, and September 5).<ref name=quintuple>Compare the [https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27199%27&START_TIME=%272048-1-1%27&STOP_TIME=%272048-9-30%27&STEP_SIZE=%271%20day%27&QUANTITIES=%2731%27 longitudes of Mercury] and the [https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27299%27&START_TIME=%272048-1-1%27&STOP_TIME=%272048-9-30%27&STEP_SIZE=%271%20day%27&QUANTITIES=%2731%27 longitudes of Venus] in the period January through September 2048, calculated by the [[JPL Horizons On-Line Ephemeris System]].</ref>

There is also a so-called quasiconjunction, when a planet in [[apparent retrograde motion|retrograde motion]]&nbsp;— always either [[Mercury (planet)|Mercury]] or [[Venus]], from the point of view of [[the Earth]]&nbsp;— will "drop back" in right ascension until it almost allows another planet to overtake it, but then the former planet will resume its forward motion and thereafter appear to draw away from it again. This will occur in the morning sky, before dawn. The reverse may happen in the evening sky after dusk, with Mercury or Venus entering retrograde motion just as it is about to overtake another planet (often Mercury ''and'' Venus are ''both'' of the planets involved, and when this situation arises they may remain in very close visual proximity for several days or even longer). The quasiconjunction is reckoned as occurring at the time the distance in right ascension between the two planets is smallest, even though, when declination is taken into account, they may appear closer together shortly before or after this.