Total Lunar Eclipse – Blue Moon (Jan 31)

January 30, 2018

What is a Blue Moon? The phrase ‘once in a blue moon’ indicates a rare event or occurrence. Most of us know the meaning of this popular saying, but have you ever wondered what a blue moon actually is? It is a phenomenon that occurs once every two or three years. A blue moon is the third full moon in an astronomical season with four full moons (the typical amount is three). Despite its name, very rarely does a blue moon appear blue.

To make things confusing, there is an alternative, definition of a blue moon. This describes ‘the second full moon in a calendar month’. Both definitions agree that a blue moon is when an extra full moon appears within a given time frame. So when you ask ‘what is a blue moon?’, it is likely that you will get two very different answers. To this day, both definitions are seen as accurate. This is despite the fact that the second definition stemmed from an erroneous misinterpretation of the original.

On January 31, there is a total lunar eclipse visible in some parts of the world; most of North America, Asia and Australia. The next total lunar eclipse is on the same date as the next blue moon. You will have the rare opportunity to witness a blue moon that actually appears blood red. The full eclipsed moon is sometimes referred to as a blood moon. Total lunar eclipses can vary in their frequency, and usually the annual number is between 0 and 3. During a total lunar eclipse, the moon is in earth’s shadow, preventing any direct sunlight from hitting its surface. Some rays of sunlight indirectly reach the moon, through the earth’s atmosphere. This gives the blood moon its striking red hue.

So the next total lunar eclipse is at the same time as the next blue moon. The moon on the day of January 31 will be a supermoon (where the full moon coincides with the moon being at its closest proximity to earth). This is fascinating for anybody with an interest in astronomy. Further to this, the next blue moon will actually be a red blood moon, and the incidence of a blue moon being blue in colour is rare indeed. This occurrence is a once-in-a-blue-moon opportunity to experience the wonder of cosmic coincidence. Being a supermoon, it will appear larger and brighter than usual.

The last time that there was a super blue moon during a total lunar eclipse was around 35 years ago, though some sources claim even longer. The next total lunar eclipse after January 31 occurs on July 27 this year. South America, Africa, Europe and Australia should be able to witness this event. It will be another year before we can expect a total lunar eclipse to be visible in America. But will it be at the same time as a blue moon? This event is not to be missed.