Supermoon fever continues this month with the third and final lunar showoff session of the year falling on the same evening as the equinox.
On March 20, the moon will be both full and at its closest point to earth along its orbital path, known to astronomers as perigee syzygy. Consequently, scientists prefer to call it a perigee moon instead of a supermoon, a term with origins in astrology rather than astronomy.
In North America, the traditional name for a full moon in March is the ‘worm moon,’ because the month often brings warmer temperatures that allow all sorts of annelids to start wriggling about a little more.
This last supermoon of the most recent series, which also gave us a ‘super blood wolf moon’ (perigee syzygy with a total lunar eclipse in January) and a ‘super snow moon’ in February, falls within hours of an equinox. In the Northern Hemisphere we think of the March equinox as ushering in spring, while it heralds the beginning of autumn south of the equator.
Of course, seasons vary pretty widely depending on your local climate, but what we can say for sure scientifically is that the sun will rise and set almost exactly due east and west, respectively, on the day of the equinox.
So bring together the worlds of astronomy, astrology and folklore and you get a ‘super worm equinox moon.’
What all this means for the casual skywatcher is that on March 20, the moon may appear up to 14 percent larger than a normal full moon. To really get a good look at the superness of the moon, you’ll want to catch it as close as possible to moonrise. Fortunately, the moon will be coming up over the horizon in the east around the same time the sun is setting in the west, making for an all-around awesome evening.
If you miss it, you’ll have to wait until February 2020 for the next supermoon.
As always, if you catch any particularly spectacular views of the super sight, please share them with me on Twitter @EricCMack.