blood moons

A dusty  atmosphere may result in sky light of a deeper red color. This causes the resulting coppery-red hue of the Moon. However there are most rare times when the moon only turns red during a lunar eclipse

On the 20th Sept. 331 B.C., before the Battle Of Gaugamela between Alexander III of Macedon (Alexander The Great) and Emperor Darius III of Persia, an eclipse of the moon was observed..Despite Alexander's army being considerably outnumbered, to astrologers of the time, the eclipse foretold Darius's defeat. As night fell on the battlefield, the eclipsed moon glowed a deep blood red, signaling blood would be spilled on that night, but not in Alexander's army.

A blood red moon is credited with saving Christopher Columbus  and his crew when their damaged ship (on his fourth voyage to the New World) was forced to land among hostile Jamaican natives in 1504 AD.