A “blood moon” or a “blood red moon” is the name used to describe the reddish hue that occurs when we have a lunar eclipse, in which the earth passes between the sun and the moon causing the moon to have a reddish appearance. When you have four “blood moons” in a relatively short period of time, it is referred to as a tetrad. Since 1492, there have apparently been only three times when a tetrad has corresponded to Jewish feast days. This current tetrad (2014–2015) marks the fourth. It will culminate on the “blood moon” that will occur on September 27–28, 2015.