According to the Old Farmer’s Almanac, this event only happens three times a century, on average. It will also be the third and final supermoon of 2019. A supermoon occurs when the full moon coincides with the moon’s closest approach of the Earth, making it appear slightly larger.
March 20, the vernal equinox in the Northern Hemisphere, will officially mark the beginning of Spring 2019 at 4:58 p.m. CDT (Get out your party hats and noise makers!) That means for most places in the world today, the day and night are almost exactly equal. The sun also rises and sets today exactly due East and West, so if you were still using a sun dial, today would be the day to calibrate it.
The full moon of March, or Full Worm Moon, will occur a little less than four hours after the equinox tonight at 8:42 p.m. CDT. At that time, the moon will appear perfectly round. This will be the closest coincidence of the vernal equinox and the full moon since 2000
Fun Fact: Without the full moon on the equinox, Easter 2019 would have been in March.