By Cynthia Germain
A past president of the Door County Astronomical Society is shedding light on the meaning of “Blue Moon” and shares information about one occurring at the end of January. The saying “once in a blue moon” gets its roots from a lunar event that typically occurs only once a year, with the next showing on January 31st. The modern definition of a Blue Moon is the appearance of a full moon in the same month. A full moon occurs approximately every 29.5 days and on the rare occasions when the full moon falls at the very beginning of a month, there is a good chance a Blue Moon will occur at the end of the month. The Blue Moon of January 31st will share added sights of a supermoon which happens when the moon is closest to Earth in its orbit and a blood moon which is a lunar eclipse that will create a reddish hue. Dr. John Beck, past-president of the Door Peninsula Astronomical Society, says that this rare occurrence is certainly a sight to see and adds that full moons have other aspects worth viewing.
This year is unique in that there will be a second Blue Moon occurring at the end of March, although without the added spectaculars of the January moon. Beyond March, a Blue Moon will not occur again until October, 2020.