In December 2018, several social media users shared a meme claiming that in 2018 the public would be experiencing a full moon on Christmas Day for the first time since 1977:
That claim was once true, but it was outdated in reference to the year 2018.
This meme first appeared online shortly before Christmas in 2015. At that time, news outlets such as Oregon Live, science blogs such as Earth and Sky, and government agencies such as NASA had published articles about the rare Christmas full moon.
Here's an excerpt from a NASA blog post dated 17 December 2015:
Not since 1977 has a full moon dawned in the skies on Christmas. But this year, a bright full moon will be an added gift for the holidays ...
This rare event won’t happen again until 2034. That’s a long time to wait, so make sure to look up to the skies on Christmas Day ...
“As we look at the moon on such an occasion, it's worth remembering that the moon is more than just a celestial neighbor,” said John Keller, NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The geologic history of the moon and Earth are intimately tied together such that the Earth would be a dramatically different planet without the moon.”
According to Space.com, the full moon of December 2018 actually occurred on the 22nd day of that month, not Christmas Day (the 25th). The next time a full moon will coincide with Christmas won't be until 2034.