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Yes, rare blue moon will be seen in October – but may not be blue

An article shared on Facebook South Africa speaks about October’s blue moon.

“Rare Blue Moon on the rise this October,” the heading reads.

“This year, a Blue Moon will light up the night sky on October 31 for the first time in decades.”

Facebook’s fact-checking system has flagged the article as possibly false. The blue moon may not actually be blue, but there is one in October 2020.

Two full moons in October

An article by the National Aeronautics and Space Administration (Nasa), an independent agency in America responsible for space research, says there will be two full moons in October 2020 – visible in the USA. 

The first full moon will be visible on 1 October , “appearing opposite the sun” and will appear full “for about three days”, Nasa says.

The second full moon, known as the “blue moon”, will occur on 31 October. So two full moons will occur in a single month.

CBS News has also reported on the full moon, saying that this “halloween full moon” will be visible in all time zones around the world. A “blue moon” last occurred in 1944. 

CBS News says it is also known as the Hunter's moon, “the first moon following the harvest moon”. 

Blue moon really blue?

Royal Museums Greenwich, an organisation comprising four museums in Greenwich, London, explains in an article that a blue moon has nothing to do with the actual colour of the Moon but rather to do with the timing of full moons during the year.

The article says that phases of the moon normally take around 29.5 days to complete, which means that 12 full moon cycles takes around 354 days, falling short of a few days in the year.

Because of this, roughly every two and a half years there is a 13th full moon which is known as the blue moon, the article says.

According to the Royal Museums Greenwich, the next blue moon should be able to be seen on August 31, 2023.

In an article about blue moons, Nasa says that the moon will most likely be a pearly-grey colour. But there have been historical accounts of an actual blue moon.

Nasa says that in 1883 the Indonesian volcano Krakatoa exploded, and the plumes of ash caused the moon to appear to be blue. 

Some of the volcano’s ash clouds had bigger particles, scattering light in the red spectrum. Colours in the other spectra of light then passed though, making the moon appear blue.

USA Today says that another reason that the moon may be blue in some pictures is usually because people use special blue camera filters or manipulate the image with PhotoShop.

So yes, there will be a rare blue moon seen in October this year, however it is most likely not blue. - Taryn Willows


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