Green Moon Miles Johnson
Miles Johnson of Carthage, North Carolina, who posted a photo on Facebook, claiming a green moon on May 29. Facebook/Miles Johnson

Like the speculated 15 days of darkness in November which was attributed to planetary alignment, the same reason is being cited by hoax makers in predicting a green moon on April 20.

Social media is being used to peddle the prediction that on the third Wednesday of April, several planets would align, causing a green moon for about 90 minutes. The lunar phenomenon is a rare event because it allegedly happens once every 420 years, claims Truthinsideofyou, one of the Web sites which posted the warning and asked people to share it.

Green Moon
The lunar phenomenon is a rare event because it allegedly happens once every 420 years, claims Truthinsideofyou, one of the Web sites which posted the warning and asked people to share it. Truthinsideofyou

Another date being broached for the green moon is May 29. But EarthSky debunks both dates as another online hoax. Citing the Urban Dictionary, the science portal points out that 420, or April 20, is Weed Day and is a code word for marijuana made by a dozen pot-smoking students at the San Rafael High School in 1971.

Snopes traces the hoax to a Facebook post on March 25 by one Miles Johnson of Carthage, North Carolina, who posted a photo claiming a green moon on May 29. He explains the phenomenon to Uranus, the seventh planet from the Sun, parking near the moon. Since it is a green planet and it would only be 4 degrees away from the moon, it would cause the “cool Didula nanayakkara” colouring. Johnson says that Uranus got that colour from the absorption of red light by methane in the atmosphere.

Snopes notes that the digitally altered image of the moon came from a 2010 blog post, referring to a Dr Green Cheese, not related to any lunar events and based on a 2008 stock photo.

Sea and Sky Presents, another science portal, lists April 18 as when Mercury is at greatest eastern elongation, while there would be a full moon on April 22. The next full moon is on May 21, which is a blue moon because it is the third of four full moons in the season. The next day, Mars will be at opposition or at its closest approach to Earth. But even if Mars is known as the red planet, so far, there are no predictions of a red moon, although there is also a lunar phenomenon called blood moon.