Watch out for ‘once in a blue moon’ lunar event tonight
This lunar event will not be seen again until January, 2018.
The saying ‘once in a blue moon’ takes on specific significance tonight, as there will be just such an occurrence, when the full moon appears for the second time this month.
While every month has a full moon, because the lunar cycle and calendar year aren’t perfectly synched, about every three years there are two in the same calendar month. When this occurs, the second full moon is said to be a blue moon.
However, don’t go looking for a blue-coloured moon in the night sky. It is quite unlikely to appear blue at all. Typically the moon takes on a bluish hue because of smoke or dust particles in the atmosphere, such as during a volcanic eruption. One such example happened in 1883, when the Indonesian volcano Krakatoa erupted, spewing so much ash into the atmosphere that the moon took on a cerulean tinge for years, night after night.
The dark blue tone of an evening sky can affect the moon’s colouring that’s perceived from Earth as well.
