Triple conjunction

Under a triple conjunction is meant an astronomical event, in which two planets or a planet and a fixed star in a short period either three times encounter in the course of their apparent loop at the time of their opposition to the Sun, or at the time of inferior conjunction, within a relatively short time. Here, the planet or the planet in general, at the first conjunction prograde move, declined in the second conjunct and prograde at the third conjunction again. At triple conjunctions three cases must be considered:

Triple conjunctions of the two inferior planets

In almost every superior conjunction of Venus leads to a triple conjunction of the two inferior planets Mercury and Venus. However, this is the second conjunct usually not seen, since both planets are almost always too close to the sun.

Triple conjunctions between Mercury and Venus are also possible when the two planets are at the same time at inferior conjunction. This event is much less common and this is the second conjunct usually not visible because of the low elongation of Mercury and Venus.

Triple conjunctions between lower and upper planets and fixed stars

If Mars is in conjunction with the Sun, it quite often comes with the inferior planets Mercury and Venus to a triple conjunction. The events with the second conjunct Mercury is due to low Sonnenelongation mostly unobservable, the other two events are due to close to the horizon and the relatively low brightness of Mars ( he is near the apogee! ) Barely visible.

In triple conjunctions between Mars and Venus are mostly all three events to track, but here is Mars because of its large Erdabstands rather unimpressive.

Triple conjunctions between the inferior planets Mercury and Venus and the outer planets Jupiter, Saturn, Uranus, Neptune and the dwarf planet Pluto, as well as fixed stars take place when these are almost the same time with an inferior conjunction of Mercury or Venus conjunct the Sun. Often this second conjunction takes place when both objects are too close to the sun in the sky, to be seen, while the other conjunctions are clearly visible, especially if Jupiter, Saturn or a brighter fixed stars in the game. In the faint planets Uranus, Neptune and Pluto observation of such events by the low in the other conjunctions elongation is difficult. Triple conjunctions between the outer planets Jupiter, Saturn, Uranus, Neptune and Pluto with Mercury and Venus are relatively frequent (at least once per decade ).

As part of the loop path occurs at each inferior conjunction of Mercury or Venus to triple conjunctions with any fixed stars. Triple conjunctions with brighter fixed stars are as common as with outer planets roughly.

Triple conjunctions between planets and fixed stars top

These are the most interesting triple conjunctions, because all three conjunctions can be easily traced, because the planets or fixed stars by the sun in the sky involved in the conjunctions have a large angular distance. Triple conjunctions between upper planets or a planet and an upper fixed star can only be done if the objects are in very short time interval in opposition to the Sun.

Triple conjunctions between the bright upper planets are very rare: so the last triple conjunctions between Mars and Jupiter 1789/90, 1836/37 and 1979/ 80 and the next triple conjunctions between Mars and Jupiter were again only in 2123 and 2169/70. Between Mars and Saturn, the last triple conjunctions 1779, 1877 (only in right ascension ) and 1945/46, were held during the next such events 2148/49, 2185 and 2187 only take place again.

Both triple conjunctions Mars - Jupiter, as well as triple conjunctions Mars -Saturn, it is possible that they are repeated at intervals of 2 years. This occurred in the case of Mars and Jupiter last 927 and 929 and will be repeated until 2742 and 2744. In the case of the triple conjunction of Mars -Saturn this was 1742/43 and 1744/45 the last of the case and will be repeated again only in the years 2185 and 2187.

The historically most significant triple conjunction of Jupiter and Saturn, the so-called Greatest conjunction, the occurrence of which is referred to in the years 7 and 6 BC as a frequent explanation for the Star of Bethlehem, found last 1682/83, 1821 (only in declination ), 1940/41 and 1981 instead. You will re-enter until the year 2238/39.

More often, triple conjunctions between Jupiter and Uranus and Jupiter and Neptune. Although they are unspectacular, but provide amateur astronomers a great way to locate this planet. The next triple conjunction between Jupiter and Neptune is 2047/48, the next between Jupiter and Uranus 2037/38 occur.

At every opposition occurs by the apparent motion of the planets always loop to any triple conjunctions with fixed stars. Triple conjunctions outer planet with bright ekliptiknahen fixed stars are rather rare; about two events per decade. Many more details can be found in the " Web Links ".

Triple conjunctions of the planets Mars and Neptune in the period 1800-2100

Conjunctions in RA

Conjunctions in ecliptic longitude

Note that conjunctions are often not held in right ascension and ecliptic longitude on the same day. It is possible that a triple conjunction in right ascension and not only in ecliptic longitude (and vice versa) can take place. A more comprehensive list from 1500 to 2500 is also found in the Book of conjunctions, occultations and transits - The little almanac of planets from Marco Peuschel. All details can be found under " Web Links ".