CNN reports that minister John Hagee points to the tetrad, which is four consecutive total lunar eclipses, each separated by six months, as a sign that something "world-shaking" would happen this month.

Prophecy believers also point to the crashing stock markets around the world as another sign that end times are near.

Ministers cite biblical scripture to support their beliefs, such as in Joel 2:30-31, in which it says, “The sun shall be turned into darkness, and the moon into blood, before the coming of the great and awesome day of the Lord." The Book of Revelation also references a “moon that became like blood.”

Other prophecy believers refer to Jonathan Cahn, author of “The Mysteries of the Shemitah,” which examines the Jewish observance of Shemitah that runs in seven-year cycles. It has been linked in the past to stock market crashes and other global calamities. Since 2014-2015 is considered to be a Shemitah year, that along with the appearance of the blood moon is considered to be an unprecedented event by some prophecy followers.

According to the astronomy website EarthSky.org, there have been 62 tetrads since the first century and their appearances follow a natural cycle which does not support a doomsday scenario.