What you need to know about March's blood moon lunar eclipse
Two eclipses will grace in sky in March — a total lunar eclipse and a partial solar eclipse — but only one of these sky-watching events will be visible to those of us in Illinois.
The partial solar eclipse on March 29 will only be visible to the far eastern part of North America, as well as northwest Africa, northern Asia and parts of Europe. Optimal viewing will be in parts of Canada, where the sun will be between 80% and 92% blocked, giving it a crescent appearance in the sky, National Geographic reports.
Earlier in the month, though, a total lunar eclipse will be visible on the night of March 13 into 14. We will be able to witness that phenomenon just like everyone else on the night side of Earth.
A total lunar eclipse occurs when Earth sits directly between the sun and the moon, causing Earth's shadow to be cast on the moon, according to NASA. This can only happen during a full moon. Not all lunar eclipses are total eclipses, as the March 14 event will be. There are two other kinds of lunar eclipses: partial lunar eclipses and penumbral lunar eclipses.
When the Earth and moon don’t line up perfectly, it creates a partial lunar eclipse. When this happens, Earth still casts a shadow on the moon, but it won’t cover it entirely, NASA reports. Instead, it looks like there is bite taken out of the moon. The third type of lunar eclipse, called a penumbral eclipse, occurs when the moon passes through Earth’s penumbra, which is the outer part of its shadow. When this happens, the moon will appear more dim than usual. Visually, these eclipses aren’t much to look at, and you likely wouldn’t even notice it is happening if you weren't aware.
The full lunar eclipse lasts about six hours, starting with the penumbral phase at 10:57 p.m. March 13 and ending at 5 a.m. March 14. The partial phase, during which it will appear a bite is taken out of the moon, will begin at 12:09 a.m. March 14, and it will reach totality — the point at which Earth is directly between the sun and the moon — at 1:26 a.m. It will then return to the partial phase and then penumbral phase before coming to an end at 5 a.m.
Total lunar eclipses are called blood moons because the moon has a reddish tint when the eclipse is in the total stage. This coloring is because of how light from the sun passes through Earth’s atmosphere, a principle called Rayleigh scattering. Sunlight moves in waves, and the different colors of light — red, orange, yellow, green, blue, indigo and violet — have different properties. When red light travels through the atmosphere, it bends, or refracts, on each side of Earth, and this allows the red light to be cast on the moon during an eclipse, according to EarthSky. This same principle is why we see the sky as blue.
A lunar eclipse will not always appear the same shade of red because it depends on the current conditions in Earth’s atmosphere, according to EarthSky. More clouds or dust in the atmosphere will make the moon look more red, while a cleaner atmosphere will make it look less red. Too much debris in the atmosphere, however, can dampen out this effect.
This is the first total lunar eclipse since November 2022, but the next total lunar eclipse will be Sept. 7. However, that lunar eclipse will not be visible in the United States because the moon will be below the horizon. The next total lunar eclipse we will be able to see here will be on March 3, 2026, NASA reports.
This year's March full moon will, of course, be called a blood moon because of the lunar eclipse, but the March full moon is also known as the worm moon, according to the Old Farmer's Almanac. Technically, that would make this year's March full moon the blood worm moon.
It was long thought that this worm moon nickname came about because it is the time of year when earthworms tend to resurface, but it turns out it has nothing to do with earthworms at all. Instead, the worm in the worm moon name refers to beetle larvae that typically start to emerge from tree bark at this time of year.
Other seasonally inspired nicknames for the March full moon include the sugar moon, because it's maple tapping season, the goose moon or eagle moon, because some Native tribes noted this was the time of year when these birds would return from their migrations, and the sore eyes moon, because the sun can appear blinding when reflected off the snowy ground.