The sight being so rare, the phrase ‘once in a blue moon’ was coined because of it.
But rather than the moon actually changing colour, a blue moon refers to when two full moons appear in the same calendar month.
The first full moon was spotted on July 1 and the second will appear on the last day of the month today – Friday July 31.
Website timeanddate.com lists the following information on blue moons: “A Moon that actually looks blue, however, 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.
“Eruptions like on Mount Krakatoa, Indonesia (1883), Mount St. Helens (1980) and Mount Pinatubo (1991) are all known to have caused blue moons.”
This appearance is the first such occurrence in three years since the last blue moon month in August 2012, the next will not be until 2018.
Astronomers predict it will only happen on 12 occasions between now and 2043.
Friday’s weather is set to be mostly clear in the East Midlands so there is a good chance of getting a good view of the phenomenon.
If you miss this Friday’s blue moon, here are your next opportunities:
January 31 2018
March 31 2018
October 31 2020
August 31 2023
May 31 2026
December 31 2028
September 30 2031
July 31 2034
January 31 2037
March 31 2037
October 31 2039
August 31 2042
For more information see www.timeanddate.com/astronomy/moon/blue-moon.html.