The worm moon is the last full moon of winter, and it is due to be visible in the night sky right at sunset on Friday.
The name refers to the time of year when worm-looking beetle larvae emerge from the bark of trees as spring approaches and temperatures warm. According to the Farmer’s Almanac, it was first recorded in the 1760s by explorer Captain Jonathan Carver while visiting the Naudowessie (also known as Sioux or Dakota) and other Native American tribes.
“These fun names [for moons] are related to something that was happening that people related to on the planet,” said Jackie Faherty, an astrophysicist at the American Museum of Natural History. “Moon cycles were a really large part of people's lives back in the day.”
The March full moon marks the transition from winter to spring, and it has many other names that allude to the seasonal revival of animals. The Algonquin tribe, which was partially based in New Jersey and southeastern New York until severe displacement by colonists, referred to it as the eagle or goose moon. The Northern Ojibwe, who inhabited parts of Canada and the northern plains, called it the “Crow Comes Back Moon.”
The Ojibwe also referred to the final cold season moon as Sugar Moon, when the sap began flowing from maple trees. The Pueblo called it Wind Strong Moon for the strong gusts of March. And the Lakota and Assiniboine named it Sore Eyes Moon because of the intense sunlight that reflected from melting snow at winter’s end.
But this moon also has religious references. In Christianity, it is known as the Paschal Full Moon if it occurs after the spring equinox and, by default, it becomes the first moon of spring. But if it comes before the spring equinox, as it does this year, then it is a Lenten Moon. This year the full moon lands on March 18th — before the spring equinox Sunday, when days continue to get longer and warmer as the northern hemisphere begins to tilt toward the sun rather than away from it. The moon reached its peak fullness at 3:17 a.m. Friday morning. But it can retain its full appearance for up to a day later — as long as its disc is more than 98% illuminated.
No matter what it’s called, Faherty said the best way to view the full moon is to find a place where the east and west are visible such as Lower Manhattan, a rooftop or even greenways along the Hudson and East Rivers. Pier 86, where the Intrepid Sea, Air & Space Museum is located, is a great place for viewing. The Rockefeller State Park Preserve, just north of Tarrytown, will be holding a “Worm Moon” hike. Tickets cost $3.
“The full moon is rising when the sun is setting,” Faherty said. “Watch the sun set [in the west], and then turn around and look for the moon rising in the east.”
Because it is brightly lit, Bart Fried, executive vice president of the Amateur Astronomers Association of New York City, doesn’t recommend binoculars or a telescope. The direct-facing sunlight makes lunar features such as craters more difficult to see because the lack of shadows reduces contrast.
“The moon is the most beautiful thing in the night sky,” Fried said. “It is something that anybody can go out and look [at with the] naked eye and appreciate.”
As for timing, Faherty recommended watching the full trajectory of the lunar ascension into the night sky. At the moment when it reaches the horizon, the moon will appear larger, a psychological effect.
“Watching a full moon rise when it’s already at its largest, most illuminated part of the disk is always a beautiful thing,” Faherty said. “You get that awe-inspiring moment of feeling like the moon is right there for you."
The next full moon, the first of spring, will happen on April 16.
Correction: A previous version of this story misspelled a reference to the Ojibwe.