For the first time in nearly two decades, the spring equinox and a full moon will coincide within hours of each other.

Wednesday, March 20, at 5:58 p.m., marks the arrival of spring or the vernal equinox. For the first time since 2000, the vernal equinox and a full moon will coincide within four hours of each other. The last time the spring equinox and a supermoon occurred of the same day was back in 1981.

According to the Old Farmer's Almanac, the March full moon is called the Worm Moon because "this time of the year, the ground begins to soften enough for earthworm casts to reappear, inviting robins and birds to feed."

The months 'Full Worm Supermoon' is the third and final supermoon of 2019. According to EarthSky.org, the next time a full moon and the spring equinox will fall less than one day apart will be March 2030.