Tritos

The tritos is an eclipse cycle of 3986.63 days. (about 1 month short of 11 years)

It corresponds to:

The length of the tritos is equal to the length of the inex minus the length of the saros eclipse cycles. Therefore, eclipses that occur 1 tritos apart (i.e. both eclipses belong to the same tritos series), belong to two different saros series with series numbers that differ by one.

The pre-Columbian Maya used a calculation in their own observations of eclipse cycles in which a period of three tritoses was approximated by 11960 days, based on 46 periods of their tzolk'in calendar (i.e. 46 × 260 days). The number of anomalistic months in a tritos (144.68), having a fraction near ​23, means every third eclipse is in nearly the same position in the elliptical orbit, so eclipses will have similar timing and total versus annular quality.

Solar and lunar eclipse event dates will repeat on this cycle for about 700 years.

Tritos saros lunar series 1000-2500
A graph of lunar eclipses, grouped by their Saros cycle and Tritos cycle

Example solar Tritos series

This eclipse is a part of a tritos cycle, repeating at alternating nodes every 135 synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee), but groupings of 3 tritos cycles (≈ 33 years minus 3 months) come close (≈ 434.044 anomalistic months), so eclipses are similar in these groupings.

Series members between 1901 and 2100
SE1904Mar17A
March 17, 1904
(Saros 128)
SE1915Feb14A
February 14, 1915
(Saros 129)
SE1926Jan14T
January 14, 1926
(Saros 130)
SE1936Dec13A
December 13, 1936
(Saros 131)
SE1947Nov12A
November 12, 1947
(Saros 132)
SE1958Oct12T
October 12, 1958
(Saros 133)
SE1969Sep11A
September 11, 1969
(Saros 134)
SE1980Aug10A
August 10, 1980
(Saros 135)
SE1991Jul11T
July 11, 1991
(Saros 136)
SE2002Jun10A
June 10, 2002
(Saros 137)
SE2013May10A
May 10, 2013
(Saros 138)
SE2024Apr08T
April 8, 2024
(Saros 139)
SE2035Mar09A
March 9, 2035
(Saros 140)
SE2046Feb05A
February 5, 2046
(Saros 141)
SE2057Jan05T
January 5, 2057
(Saros 142)
SE2067Dec06H
December 6, 2067
(Saros 143)
SE2078Nov04A
November 4, 2078
(Saros 144)
SE2089Oct04T
October 4, 2089
(Saros 145)
SE2100Sep04T
September 4, 2100
(Saros 146)

See also

References

  • Mathematical Astronomy Morsels, Jean Meeus, Willmann-Bell, Inc., 1997 (Chapter 9, p. 51, Table 9.A Some eclipse Periodicities)

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