Worm Moon: March's full moon

Where the name Worm Moon comes from

March’s popular name is one of the few where the main source openly offers two explanations.

The more familiar story, retold by the Old Farmer’s Almanac, ties the name to earthworms. As the ground thaws, worms come back up to the surface. The Farmers’ Almanac, a separate publication based in Maine, treats the name more generally, as a sign that spring is coming.

The Old Farmer’s Almanac also gives a second reading. In the 1760s, the explorer Jonathan Carver wrote that this moon’s “worm” meant something else: larvae that emerge from tree bark and other winter hiding places. Carver’s account is a colonial traveler’s secondhand record of names he heard from Native peoples. It is a historical source, but not a tribal one.

Both versions are about the same thing: the first signs of life after winter. Neither one comes from a single “Native American calendar.” The common list of twelve names was assembled by almanacs from Indigenous, colonial and European sources. The original Indigenous names varied by nation and dialect and often described a whole lunar month. The full moon names overview has the background.

Other names for March’s full moon

The Old Farmer’s Almanac lists these names, each with the nation it credits. We report the almanac’s attributions as it gives them. We have not confirmed them with the nations.

• Sugar Moon: Ojibwe. This is maple-sap season.
• Crow Comes Back Moon: Northern Ojibwe.
• Snow Crust Moon: Anishinaabe.
• Sore Eyes Moon: Dakota, Lakota and Assiniboine.
• Eagle Moon: some Cree groups.
• Goose Moon: Algonquin and Cree.
• Wind Strong Moon: Pueblo.

Indian Country Today (ICT), a Native-run news outlet, gives the Ojibwe name Onaabani-giizis, which it translates as Hard Crust on the Snow Moon. It describes the hard crust on late-winter snow, the same idea behind Snow Crust Moon above.

ICT adds that this is not uniform even within Ojibwe: communities on the western side of Lake Superior use Hard Crust on the Snow Moon for March, while the milder eastern side calls March the Maple Sugar Moon, a name the west uses a month later. ICT’s Dakota list gives Ištá wičháyazaŋ wí, the Sore Eyes Moon, and explains it as snow blindness. The Oneida name translates as “The Day Is Cut in Two,” which ICT glosses as split days. Unexpectedly for anyone used to the almanac list, the 1890s Cherokee seminary calendar calls March Anvyi, the Strawberry Moon.

What makes the Worm Moon notable

March’s full moon sits right on the seasonal boundary. Depending on the year, it comes before or after the March equinox, so it can be the last full moon of winter or the first full moon of spring. Compare the dates in the table above with the equinox, which falls around March 20.

It also helps set the date of Easter. The US Naval Observatory explains the rule used by Western churches: Easter is the first Sunday after the first full moon that falls on or after March 21. That full moon is an “ecclesiastical” one, worked out from church tables, not the astronomical full moon shown on this page. The two usually agree closely, but not always, and the difference occasionally moves Easter. Depending on the year, the full moon that counts is March’s or April’s.

As spring approaches, the full moon no longer climbs as high as it did in midwinter. A full moon sits opposite the Sun, and as the Sun’s path rises toward summer, the full moon’s path sinks.

How to watch the Worm Moon

Look for it at moonrise. A full moon rises in the east close to sunset, and the table above shows the moonrise time for major cities on the best evening. The first half hour after it rises is the most colorful. Low moonlight passes through a long path of air, which scatters away the blue and leaves a yellow or orange glow.

The Moon will also look oversized near the horizon. NASA explains that this Moon illusion happens in your head, not in the sky: photos show the Moon is the same width at moonrise as when it is high overhead. To prove it to yourself, look at the low Moon through a cardboard tube. With the trees and rooftops hidden, it shrinks back to normal.

On the night of full moon the sky is too bright for faint stars, so this is a night for the Moon itself. Binoculars braced against a post or a car roof show the dark plains of the near side clearly. For dark-sky targets, check our city sky pages for the moon-free evenings a week or two later.