On April 15, millions of people around the world marveled at the "bloody" spectacle caused by a total lunar eclipse. The eclipse was the first of a series of four total lunar eclipses, which some religious groups see at a sign of the end of times.

The April 15 eclipse was the start of what astronomers refer to as a lunar tetrad. This phenomenon occurs when four total lunar eclipses occur in a relatively short period of time without any partial eclipses happening in between. Some Christian pastors have interpreted the current lunar tetrad as a sign of Jesus' second coming.

The eclipse last Tuesdays lasted for around 78 minutes bathing the world in an eerie red glow. Moon watchers from North and South America were also treated to a VIP show of the cosmic dance with the Western Hemisphere getting the best view of the event. Scientists say that the next eclipse will happen this coming Oct. 8. The last two eclipses of the tetrad will occur next year with the third eclipse occurring on April 4 and the last one occurring on Sept. 28.

While lunar tetrads are considered as somewhat of a rarity in the scientific community, astronomers say that they do happen and they can also be predicted with a fair amount of accuracy. However, this has not stopped some religious leaders from linking the series of eclipse to predictions of the end of the world. These predictions may stem from a number of verses in the Bible that mentions a "bloody" moon.

"The sun shall be turned into darkness, and the moon into blood, before the great and terrible day of the Lord," says Joel 2:31. Another similar quote can also be seen in the New Testament. "The sun shall be turned into darkness, and the moon into blood, before the great and notable day of the Lord."

Some religious leaders have also been quick to note that each of the eclipses in the current lunar tetrad fall on significant Jewish holidays such as the Passover and the Feast of Tabernacles. There are also a number of recently published books that discuss the current tetrad including a book by Texan pastor John Hagee. Hagee's book is entitled "Four Blood Moons: Something Is About to Change."

Hagee's latest book has rapidly risen through the ranks of the New York Time's Advice/how to bestseller list and is now ranked number 4. Despite the current doom and gloom predictions linked to the lunar tetrad, NASA has reiterated that while lunar tetrads are not exactly common, they aren't exceedingly rare either. The agency has also stated that there will be a total of 8 lunar tetrads that will occur before 2100.