What Is a Tetrad?

A blood moon tetrad is a sequence of four consecutive total lunar eclipses — each separated by six months — with no partial eclipses in between. During a total lunar eclipse, the moon passes through Earth's shadow and takes on a reddish hue from sunlight refracted through Earth's atmosphere. This is the "blood moon" of Joel 2:31 and Acts 2:20.

NASA's catalog of lunar eclipses documents that tetrads are relatively rare — occurring only eight times in the 20th and 21st centuries combined. What Pastor Mark Biltz discovered in 2008, by cross-referencing NASA's eclipse data with the Jewish calendar, is that three of the tetrads in the last 500 years fell on the Jewish feast days of Passover and Tabernacles — twice in a row, in both years of the tetrad.

The Historical Pattern

Three tetrads have fallen on Jewish feast days in the past 500 years:

1493-1494: The year Spain expelled its Jewish population (1492) and Columbus sailed to the Americas. The tetrad fell on Passover and Tabernacles in both 1493 and 1494.

1949-1950: Israel declared independence on May 14, 1948. The first war of Israeli independence concluded. The tetrad fell on Passover and Tabernacles in 1949 and 1950.

1967-1968: The Six-Day War, in which Israel captured Jerusalem for the first time since 70 AD. The tetrad fell on Passover and Tabernacles in 1967 and 1968.

In each case, the tetrad bracketed a significant event in Jewish history. The pattern was identified retrospectively from NASA data — not predicted in advance.

The 2014-2015 Tetrad

The most recent feast-day tetrad occurred in 2014-2015, falling on Passover and Tabernacles in both years. This tetrad was identified in advance by Biltz and Hagee based on NASA's eclipse predictions and attracted significant attention in prophetic circles.

The question of what event it brackets remains open. Some have pointed to the rise of ISIS in 2014, the Israeli military operations in Gaza, and subsequent shifts in Middle Eastern geopolitics. Others note that the pattern in previous tetrads has been that the significant event often occurs near — but not always during — the tetrad itself.

The next feast-day tetrad after 2014-2015 does not occur for centuries. Whatever the 2014-2015 tetrad signified or did not signify, it was the last such alignment for the foreseeable future.