Wednesday night's supermoon, officially called the Super Worm Moon, was the last supermoon of the year. The full moon fell on the Vernal Equinox, the first day of spring in the Northern Hemisphere.

The March 20 moon was the third of three back-to-back supermoons, February's being the biggest and brightest moon of 2019.

According to Space.com, a supermoon is when a full moon coincides with the moon's perigee, or closest approach to Earth in orbit. Since the moon's orbit is elliptical rather than circular, its distance from the Earth varies.

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(MORE: The Science Behind the First Day of Spring)

The moon reached complete fullness at 9:43 p.m. EST, a little less than four hours after the equinox's arrival at 5:58 p.m.

March's moon is named the "worm moon." NBC reported that the name comes from folklore tradition, as it's usually the time of year the ground begins to thaw and earthworms are prevalent.

MORE FROM WEATHER.COM: Photos of the Biggest and Brightest Moon of 2019