Solar eclipse of December 14, 1917

This eclipse is a member of a semester series. An eclipse in a semester series of solar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.[1]

Solar eclipse series sets from 1916–1920
Ascending node			Descending node
111	December 24, 1916 Partial		116	June 19, 1917 Partial
121	December 14, 1917 Annular		126	June 8, 1918 Total
131	December 3, 1918 Annular		136	May 29, 1919 Total
141	November 22, 1919 Annular		146	May 18, 1920 Partial
151	November 10, 1920 Partial

Solar saros 121, repeating every about 18 years, 11 days, and 8 hours, contains 71 events. The series started with a partial solar eclipse on April 25, 944. It contains total eclipses from July 10, 1070, to October 9, 1809. It contains hybrid eclipses on October 20, 1827, and October 30, 1845. It contains annular eclipses from November 11, 1863, to February 28, 2044. The series ends at member 71 as a partial eclipse on June 7, 2206. The longest total eclipse occurred on June 21, 1629, with greatest duration of totality at 6 minutes and 20 seconds. The longest annular eclipse will occur on February 28, 2044, with greatest duration of annularity at 2 minutes and 27 seconds.[2]

Series members 49–65 occur between 1801 and 2100:
49	50	51
October 9, 1809	October 20, 1827	October 30, 1845
52	53	54
November 11, 1863	November 21, 1881	December 3, 1899
55	56	57
December 14, 1917	December 25, 1935	January 5, 1954
58	59	60
January 16, 1972	January 26, 1990	February 7, 2008
61	62	63
February 17, 2026	February 28, 2044	March 11, 2062
64	65
March 21, 2080	April 1, 2098

The metonic series repeats eclipses every 19 years (6939.69 days), lasting about 5 cycles. Eclipses occur in nearly the same calendar date. In addition, the octon subseries repeats 1/5 of that or every 3.8 years (1387.94 days).

21 eclipse events between July 21, 1906 and July 20, 1982
July 20–21	May 9	February 24–25	December 13–14	October 1–2
105	107	109	111	113
			December 13, 1898
115	117	119	121	123
July 21, 1906	May 9, 1910	February 25, 1914	December 14, 1917	October 1, 1921
125	127	129	131	133
July 20, 1925	May 9, 1929	February 24, 1933	December 13, 1936	October 1, 1940
135	137	139	141	143
July 20, 1944	May 9, 1948	February 25, 1952	December 14, 1955	October 2, 1959
145	147	149	151	153
July 20, 1963	May 9, 1967	February 25, 1971	December 13, 1974	October 2, 1978
155
July 20, 1982