THE expression "once in a blue moon" has a long history of being used to describe rare events.
Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
But, this Friday evening Dubbo residents will have a clear view of a blue moon, which has not appeared in the night sky since 2012.
In astronomy, a blue moon is said to be the second full moon in a month.
The chances of seeing two full moons within the same month is a phenomenon that only takes place once every 30 months.
The reason for this occurring falls back on the length of a calendar month on Earth not equaling a lunar month.
A lunar month is about 29 days long whereas most of the calendar months are 30 or 31 days long.
Despite the name, the moon will not adopt a blue tinge to its golden white colour.
A moon that actually looks blue is a very rare sight.
The moon, full or any other phase, can appear blue when the atmosphere is filled with dust or smoke particles of a certain size after a dust storm or a volcanic eruption.
Eruptions like on Mt. Krakatoa, Indonesia in 1983 and Mt. St Helens, America in 1980 have both been known to have caused blue moons.