Cycle of the moon during its approx 28 day revolution around earth. Great science / astronomy pin, The full moon = red, called BLOOD MOON on 8 Oct 2014... a previous one was the week before Easter (2014) and two more are coming in 2015. NASA (APOD) says that 4 blood moons in 365 day cycle is very unusual. RESEARCH #DdO:) - MOST POPULAR RE-PINS - http://www.pinterest.com/DianaDeeOsborne/universe-lights/ - Very nice UNIVERSE LIGHTS. Pin via Liu Prato.