Triple conjunction

The triple conjunction is the three-time apparent meeting of two planets in the starry sky if it occurs within a few months.

While simple encounters take place from quarterly (for Mercury and Venus) to a 20-year rhythm (for Jupiter and Saturn), depending on the period of rotation of the planets, triple conjunctions are only possible if the encounter takes place during the annual planetary loops. These loops come about because the earth orbits the sun in the same direction as all other planets. The first and third conjunction take place in the right direction (in the starry sky from right to left), while the second is retrograde .

Sometimes one speaks of a triple conjunction when a planet repeatedly encounters a bright fixed star on its loop . However, only five stars that are close to the ecliptic are suitable for this. If you also include stars of the 2nd magnitude, there are around twenty.

Triple conjunctions of the two lower planets

If Venus comes into upper conjunction (i.e., its orbit beyond the Sun) about every 19 months , it will be triple conjunction with Mercury almost every time over a period of 5 months. However, the second conjunction of this is rarely seen, since both lower planets are then very close to the sun.

Triple conjunctions between Mercury and Venus are also possible when the two planets are in lower conjunction at the same time. This event is much rarer and here, too, the second conjunction is mostly not visible because of insufficient elongation of Mercury and Venus.

Triple conjunctions between lower and upper planets

When the planet Mars wanders past the sun ( conjunction ), there is often a triple conjunction with the lower planets Mercury and Venus. Given to those with Mercury conjunct the second because of low sun distance is usually unobservable, but are also the two other events because close to the horizon and the relatively low brightness Mars (he is near the apogee!) Freiäugig almost never see.

With triple conjunctions between Mars and Venus, all three events can usually be followed, but Mars is rather inconspicuous because of its great distance from the earth. It is more attractive in a five- to eight-inch telescope because the Venus crescent contrasts well with the tiny disc of Mars.

Relatively common (at least once a decade) are triple conjunctions between the lower planets Mercury and Venus and the outer planets Jupiter , Saturn , Uranus and Neptune . They can take place when the distant planets pass behind the sun at about the same time as a lower conjunction of Mercury or Venus. For the second conjunction, however, they are usually too close to the sun for successful observation. The first and third conjunction are clearly visible when it comes to Jupiter, Saturn or a brighter fixed star . However , observation of the very distant planets Uranus, Neptune and the dwarf planet Pluto is very difficult due to their low brightness.

While going through the planetary loop , every lower conjunction of Mercury or Venus leads to triple conjunctions with some fixed stars. With stars first size are as common as having outer planets roughly.

Triple conjunctions between upper planets or fixed stars

These are the most interesting triple conjunctions, because all three conjunctions can easily be traced, since the planets or fixed stars involved in the conjunctions are at a large angular distance from the sun in the sky . Triple conjunctions between upper planets or an upper planet and a fixed star can only occur if these objects are in opposition to the sun within a very short time.

Triple conjunctions between the bright upper planets are very rare: the last triple conjunctions between Mars and Jupiter were in 1789/90, 1836/37 and 1979/80 and the next triple conjunctions between Mars and Jupiter were not again until 2123 and 2169/70 . The last triple conjunctions between Mars and Saturn took place in 1779, 1877 (only in right ascension) and 1945/46, while the next such events only take place again in 2148/49, 2185 and 2187.

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

The historically particularly significant triple conjunction of Jupiter and Saturn, the so-called greatest conjunction , whose occurrence in the years 7 and 6 BC. Chr. Is called a frequent explanation for the star of Bethlehem , took place last in 1682/83, 1821 (only in declination ), 1940/41 and 1981. It will not occur again until 2238/39.

More common are triple conjunctions between Jupiter and Uranus and Jupiter and Neptune. While unspectacular, they are a great way for amateur astronomers to find these planets. The next triple conjunction between Jupiter and Neptune will occur in 2047/48, the next between Jupiter and Uranus in 2037/38.

With every opposition there is always some kind of threefold conjunctions with fixed stars due to the apparent loop movement of the planets. Triple conjunctions of outer planets with bright ecliptic fixed stars are rather rare; about two events per decade.

Triple conjunctions of the planets Mars to Neptune in the period from 1800 to 2100

Conjunctions in right ascension

year	Planets involved	1st conjunction	2. conjunction	3. conjunction
1821	Uranus-Neptune	17. March	May 7th	2. December
1821	Jupiter-Saturn	25th June	November 23	23rd of December
1836/37	Mars-Jupiter	November 14, 1836	March 5, 1837	March 23, 1837
1843	Jupiter-Neptune	9th April	September 15th	November 5th
1845	Mars Neptune	18th of June	September 2nd	October 3
1846	Saturn-Neptune	March 31	September 14th	3rd of December
1851/52	Saturn-Uranus	July 15, 1851	October 4, 1851	March 4, 1852
1877	Mars-Saturn	July 27th	26th of August	November 4th
1888	Mars-Uranus	January 9th	5th of May	June 7th
1896/97	Mars Neptune	September 24, 1896	December 12, 1896	February 19, 1897
1896/97	Saturn-Uranus	December 28, 1896	June 19, 1897	August 26, 1897
1907	Mars-Uranus	2.May	July 19	August 24th
1919/20	Jupiter-Neptune	September 23, 1919	March 13, 1920	April 20, 1920
1927/28	Jupiter-Uranus	July 9, 1927	August 19, 1927	January 23, 1928
1932/33	Mars Neptune	December 5, 1932	March 11, 1933	May 16, 1933
1940/41	Jupiter-Saturn	August 15, 1940	October 12, 1940	February 20, 1941
1943/44	Mars-Uranus	September 9, 1943	December 26, 1943	January 20, 1944
1945/46	Mars-Saturn	October 26, 1945	January 22, 1946	March 19, 1946
1952/53	Saturn-Neptune	November 18, 1952	May 31, 1953	July 11, 1953
1954/55	Jupiter-Uranus	October 8, 1954	January 6, 1955	May 10, 1955
1964/65	Mars-Uranus	5th December 1964	April 3, 1965	May 6, 1965
1968/69	Jupiter-Uranus	December 9, 1968	March 15, 1969	18th July 1969
1971	Jupiter-Neptune	February 2nd	May 20th	September 18
1979/80	Mars-Jupiter	December 13, 1979	March 2, 1980	May 4th 1980
1981	Jupiter-Saturn	January 14th	19th of February	30th July
1983	Jupiter-Uranus	February 17th	May 16	September 24th
1988	Saturn-Uranus	13th February	June 27th	October 18
1989	Saturn-Neptune	3 March	June 24th	November 12th
1993	Uranus-Neptune	January 26th	17th of September	September 28th
2009	Jupiter-Neptune	25. May	July 13th	20th of December
2010/11	Jupiter-Uranus	June 6, 2010	September 22, 2010	January 2, 2011
2025/26	Saturn-Neptune	June 29, 2025	August 6, 2025	February 16, 2026
2037/38	Jupiter-Uranus	September 8, 2037	February 19, 2038	March 30, 2038
2041/42	Mars-Uranus	November 2, 2041	March 16, 2042	March 18, 2042
2047/48	Jupiter-Neptune	July 24, 2047	November 15, 2047	February 26, 2048
2063	Mars-Uranus	February 23	May 27th	17th July
2066	Jupiter-Uranus	January 19th	June 27th	18th of August
2071/72	Mars Neptune	October 8, 2071	February 5, 2072	February 29, 2072
2079	Saturn-Uranus	February 28	29th August	23rd October
2085/86	Jupiter-Neptune	October 30, 2085	January 13, 2086	June 8, 2086
2088/89	Mars Neptune	December 14, 2088	January 4, 2089	May 13, 2089
2093	Jupiter-Uranus	May 16	October 27	30th of November

Conjunctions in ecliptical length

year	Planets involved	1st conjunction	2. conjunction	3. conjunction
1821	Uranus-Neptune	March 22	May 3rd	3rd of December
1836/37	Mars-Jupiter	November 15, 1836	February 28, 1837	March 29, 1837
1843	Jupiter-Neptune	9th April	12th September	November 8th
1845	Mars Neptune	June 21st	August 22nd	8th October
1846	Saturn-Neptune	4. April	5th September	11th December
1888	Mars-Uranus	11th January	May 4th	June 5th
1896/97	Mars Neptune	September 24, 1896	December 13, 1896	February 18, 1897
1897	Saturn-Uranus	6th January	June 1st	the 9th of September
1907	Mars-Uranus	2.May	17th July	26th of August
1919/20	Jupiter-Neptune	September 24, 1919	March 8, 1920	April 24, 1920
1927/28	Jupiter-Uranus	July 15, 1927	August 11, 1927	January 25, 1928
1932/33	Mars Neptune	December 6, 1932	March 7, 1933	May 17, 1933
1940/41	Jupiter-Saturn	August 8, 1940	October 20, 1940	February 15, 1941
1943/44	Mars-Uranus	September 9, 1943	December 30, 1943	January 16, 1944
1945/46	Mars-Saturn	October 27, 1945	January 20, 1946	March 20, 1946
1952/53	Saturn-Neptune	November 21, 1952	17th May 1953	July 22, 1953
1954/55	Jupiter-Uranus	October 7, 1954	January 7, 1955	May 10, 1955
1964/65	Mars-Uranus	December 6, 1964	March 29, 1965	May 8, 1965
1968/69	Jupiter-Uranus	December 11, 1968	March 11, 1969	20th July 1969
1971	Jupiter-Neptune	February 1st	May 22	16th September
1979/80	Mars-Jupiter	December 16, 1979	February 27, 1980	May 5th 1980
1980/81	Jupiter-Saturn	December 31, 1980	March 4th 1981	July 24, 1981
1983	Jupiter-Uranus	February 18	May 14th	25th of September
1988	Saturn-Uranus	13th February	June 26th	October 18
1989	Saturn-Neptune	3 March	June 24th	November 13th
1993	Uranus-Neptune	February 2nd	August 19th	October 25
2009	Jupiter-Neptune	May 27th	10th of July	21st December
2010/11	Jupiter-Uranus	June 8, 2010	September 19, 2010	January 4, 2011
2037/38	Jupiter-Uranus	September 8, 2037	February 19, 2038	March 30, 2038
2041/42	Mars-Uranus	November 2, 2041	March 5, 2042	March 28, 2042
2047/48	Jupiter-Neptune	July 22, 2047	November 16, 2047	February 24, 2048
2063	Mars-Uranus	February 24th	28th of May	15th of July
2066	Jupiter-Uranus	January 20th	June 24th	August 21
2071/72	Mars Neptune	October 8, 2071	February 2, 2072	March 3, 2072
2079	Saturn-Uranus	February 26th	August 31	October 21
2085/86	Jupiter-Neptune	November 1, 2085	January 10, 2086	June 10, 2086
2093	Jupiter-Uranus	17th of May	October 21	December 5th

Note that right ascension and ecliptical longitude conjunctions often do not occur on the same day.
It is possible that a triple conjunction can only take place in right ascension and not in ecliptical length (and vice versa). A more extensive list from 1500 to 2500 can also be found in the book Conjunctions, Coverings and Transits - The Little Almanac of the Planets by Marco Peuschel.

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