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By David Meade, 21st Space Wing
/ Published February 06, 2018
A rare super blue blood moon sets in the western sky this morning at Will Rogers Air National Guard Base in Oklahoma City, Jan. 31, 2018. This lunar event hasn't happened since 1866. (U.S. Air National Guard photo by Staff Sgt. Tyler Woodward)
SAN DIEGO, Calif. -- The super blue blood moon shines bright over the San Antonio-class amphibious transport dock USS Anchorage (LPD 23), Jan. 31, 2018. The combination of a lunar eclipse, blood moon and super moon was seen for the first time in 152 years. (U.S. Navy photo by Petty Officer 2nd Class Brandon Williams-Church)
SAN DIEGO, Calif. – A sailboat floats near the western cliffs of Navy Base Point Loma, California in front of the moon. The combination of a lunar eclipse, blood moon and super moon was seen for the first time in 152 years. (U.S. Navy photo by Petty Officer 1st Class Charles White)
Super blue blood moon. The name sounds like something from a science fantasy story, but North America had the best view of this lunar event on Jan. 31, 2018. According to the National Aeronautics and Space Administration (NASA), it is the rare combination of three different lunar events. So rare, the last one occurred in 1866.
The Moon orbits around the Earth in an elliptical orbit, similar to some satellites the 21st Operations Group track in space. Instead of a perfect circle keeping the Moon the same distance from the Earth at all times, its elliptical journey brings it closer or farther away. A super moon occurs when the Moon is closest to Earth in its orbit which is known as its perigee. When the Moon is at its farthest, it’s known as its apogee.
“Once in a blue moon,” is a common expression meaning something that rarely happens. A phrase dating back to early 1500s according to Phillip Hiscock, Memorial University professor in Newfoundland, in a national news article.
“The phrase was a kind of metaphor for absurdity or impossibility,” said Hiscock in the article. This explains why a blue moon is not actually blue in color, but rather its original meaning of impossible.
"It sort of slipped sideways from impossibility to a temporal notion of impossible in time," Hiscock said. This gave way to what we know today, as a blue moon occurs whenever a second full moon arises in the same month as the previous one.
Now we add the third ingredient: blood. OK, not really. As the Moon passes through the Earth’s shadow, also known as the umbra, it takes on a reddish tint. This coloration led to the term blood moon.
According to NASA, when the Moon is completely in the umbra of the Earth, the Sun’s light is still able to reach the Moon but is filtered to the color red by the Earth’s atmosphere. The same reason the sky turns a brilliant orange-red during sunsets and sunrises.
Toss them all together and we now have a super blue blood moon. If you missed this year’s, fear not. The last occurrence was more than 150 years ago, but the next one is only 19 years away according to the NASA lunar calendar. Mark your calendars for Jan. 31, 2037.