Tetrad (astronomy)

File:Total penumbral eclipse frequency by century.png

The frequency of tetrads varies by century with the frequency of total lunar eclipses.

In astronomy, a tetrad is a set of four total lunar eclipses within two years.

List of tetrad events

1949-2000

Saros	Date Viewing	Type Chart		Saros	Date Viewing	Type Chart
1949-1950
Descending node				Ascending node
121	1949 Apr 13	Total		126	1949 Oct 07 80px	Total 80px
131	1950 Apr 02 80px	Total		136	1950 Sep 26 80px	Total 80px
1967-1968
Descending node				Ascending node
121	1967 Apr 24 80px	Total 80px		126	1967 Oct 18 80px	Total 80px
131	1968 Apr 13 80px	Total 80px		136	1968 Oct 6 80px	Total 80px
1985-1986
Descending node				Ascending node
121	1985 May 04 80px	Total 80px		126	1985 Oct 28 80px	Total 80px
131	1986 Apr 24 80px	Total 80px		136	1986 Oct 17 80px	Total 80px

2001-2051

Saros	Date Viewing	Type Chart		Saros	Date Viewing	Type Chart
2003-2004
Descending node				Ascending node
121	2003 May 16	total		126	2003 Nov 09	total
131	2004 May 04	total		136	2004 Oct 28	total
2014-2015
Ascending node				Descending node
122	2014 Apr 15	Total		127	2014 Oct 08	Total
132	2015 Apr 04	Total		137	2015 Sep 28	Total
2032-2033
Ascending node				Descending node
122	2032 Apr 25 80px	Total 80px		127	2032 Oct 18 80px	Total 80px
132	2033 Apr 14	Total		137	2033 Oct 08 80px	Total 80px
2043-2044
Descending node				Ascending node
123	2043 Mar 25 80px	Total 80px		128	2043 Sep 19 80px	Total 80px
133	2044 Mar 13 80px	Total 80px		138	2044 Sep 07 80px	Total 80px
2050-2051
Ascending node				Descending node
122	2050 May 06 80px	Total 80px		127	2050 Oct 30 80px	Total 80px
132	2051 Apr 26	Total		137	2051 Oct 19	Total

See also

• Total penumbral lunar eclipse#Summary frequency of total penumbral, total umbral and tetrad events 501–2500 for statistics by century