TimeandDate’s definition is: “A Full or New Moon that occurs when the centre of the Moon is less than 360,000 kilometres (ca. 223,694 miles) from the centre of Earth.”
Astrologer Richard Nolle, who coined the name Supermoon, similarly thinks Sunday’s Full Moon won’t make the cut.
By his reckoning, there will be two Supermoons this year, in April and May respectively.
Astronomer Bruce McClure of EarthSky.org said: “If you define a Supermoon based on the year’s closest perigee and farthest apogee, then the March 2021 Full Moon is not a Supermoon.
“If you define a Supermoon based on the perigee and apogee for a given monthly orbit, then it is a Supermoon. Take your choice!”