Though St. Patrick's has come and gone, there is another green-centric "holiday" coming in April: Weed Day. Cannabis enthusiasts unite every April 20, or 4/20, and blaze it up. Perhaps out of preemptive excitement, a Weed Day partaker got high and decided to spread an astronomical rumor about the moon turning green on April 20 — as if the cosmos wanted to vicariously celebrate the wonders of marijuana with us. Unfortunately, though the moon can turn blood red, it cannot turn green without photoshop. But that hasn't stopped gullible people from blowing smoke.
According to Snopes, the rumor of a green moon originally started when a Facebook user posted a save-the-date, informing people that the moon would turn green on May 29, 2016, before it was changed to the convenient April 20 date. The astronomical phenomenon that happened every 420 years was apparently due to the alignment of Uranus in proximity to our moon and Sun — the very fact that Uranus was mentioned probably should have tipped people off of the hoax.
Of course, there were the reasonable few who were incredulous at the prospect of a green moon.
FWIW, if you want to see a full moon, there will be one two days later on April 22, dubbed "Pink Moon." Before you ask: No, it won't actually be "pink."
According to FullMoonPhases.com, the pink moon is named after the "herb moss pink, or wild ground phlox, which is one of the earliest widespread flowers of the spring." Other names given to the full moon in April include sprouting grass moon, egg moon and fish moon.
h/t Penn Live