Solar eclipse of October 21, 1930

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 1928–1931
Ascending node			Descending node
117	May 19, 1928 Total (non-central)		122	November 12, 1928 Partial
127	May 9, 1929 Total		132	November 1, 1929 Annular
137	April 28, 1930 Hybrid		142	October 21, 1930 Total
147	April 18, 1931 Partial		152	October 11, 1931 Partial

It is a part of Saros cycle 142, repeating every 18 years, 11 days, containing 72 events. The series started with partial solar eclipse on April 17, 1624. It contains one hybrid eclipse on July 14, 1768, and total eclipses from July 25, 1786 through October 29, 2543. The series ends at member 72 as a partial eclipse on June 5, 2904. The longest duration of totality will be 6 minutes, 34 seconds on May 28, 2291. All eclipses in this series occurs at the Moon’s descending node.[2]

Series members 17–41 occur between 1901 and 2359
17	18	19
October 10, 1912	October 21, 1930	November 1, 1948
20	21	22
November 12, 1966	November 22, 1984	December 4, 2002
23	24	25
December 14, 2020	December 26, 2038	January 5, 2057
26	27	28
January 16, 2075	January 27, 2093	February 8, 2111
29	30	31
February 18, 2129	March 2, 2147	March 12, 2165
32	33	34
March 23, 2183	April 4, 2201	April 15, 2219
35	36	37
April 25, 2237	May 7, 2255	May 17, 2273
38	39	40
May 28, 2291	June 9, 2309	June 20, 2327
41
June 30, 2345

This eclipse is a part of the long period inex cycle, repeating at alternating nodes, every 358 synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee). However, groupings of 3 inex cycles (≈ 87 years minus 2 months) comes close (≈ 1,151.02 anomalistic months), so eclipses are similar in these groupings.

Inex series members between 1901 and 2100:
November 11, 1901 (Saros 141)	October 21, 1930 (Saros 142)	October 2, 1959 (Saros 143)
September 11, 1988 (Saros 144)	August 21, 2017 (Saros 145)	August 2, 2046 (Saros 146)
July 13, 2075 (Saros 147)