Tetrad (astronomy) explained

In astronomy, a tetrad is a set of four total lunar eclipses within two consecutive years.^[1]

The frequency of tetrads varies by century with the frequency of total lunar eclipses. This repeating cycle is called a tetradia. See Eclipse cycle for more information.

List of tetrad events

2001–51

See also

• for statistics by century
• Blood moon prophecy Apocalyptic preaching of John Hagee and Mark Biltz in part based on the observed phenomenon.

Notes and References

1. http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1980JRASC..74..291M&defaultprint=YES&filetype=.pdf Total Penumbral lunar eclipses, Jean Meeus, 1980