Blood Moon: What It Is, Why It Looks Red, and When the Next One Happens
Quick Reference
- What it is: A blood moon is a total lunar eclipse, when Earth’s shadow falls completely across the Moon and the Moon turns deep red or copper.
- Why red: Earth’s atmosphere bends red wavelengths of sunlight through the shadow and onto the Moon. Same physics as a sunset.
- NASA terminology: NASA calls it a “totally eclipsed Moon,” not a blood moon. The blood-moon name is popular and traditional.
- Frequency: Up to 3 total lunar eclipses per year, sometimes none.
- Duration: Totality lasts about 1 hour. The full eclipse, including partial phases, runs about 3.5 hours.
- Next ones: March 3, 2026 (Asia and the Pacific). Future US-visible eclipses follow on a published NASA schedule.
A blood moon is a total lunar eclipse seen from the night side of Earth, when the Moon passes through Earth’s deepest shadow and turns a deep copper or red. The color is not symbolism. It is sunset light, refracted through Earth’s atmosphere and projected onto the Moon’s surface, the same physics that turns the western sky orange every evening. Below is what a blood moon is, why it is red, when the next ones happen, and what NASA actually calls it.
A Blood Moon Is a Total Lunar Eclipse
Lunar eclipses happen when Earth lines up directly between the Sun and the Moon, casting a shadow on the lunar surface. There are three kinds. Penumbral eclipse: the Moon passes through the lighter outer shadow only. Subtle. Partial eclipse: part of the Moon enters the deepest shadow (umbra). Visible darkening of one edge. Total eclipse: the entire Moon enters the umbra. The Moon glows deep red. That is the blood moon.
Per NASA, the agency itself does not officially use “blood moon.” The technical term is “totally eclipsed Moon.” The popular name predates the space age and stuck because it captures what the eye sees. Both terms describe the same event.
Why Does the Moon Turn Red?
During a total lunar eclipse, the Sun is hidden behind Earth from the Moon’s perspective. Direct sunlight cannot reach the Moon. But Earth has an atmosphere, and the atmosphere bends light. Sunlight passing through the edge of Earth’s atmosphere refracts inward; blue and violet wavelengths scatter away (the same scattering that makes the sky blue), and longer red and orange wavelengths bend through and continue onto the Moon. The result is a faint copper-red glow, made entirely of every sunrise and sunset on Earth, projected at the same time onto the lunar disk.
The shade can vary from a dark brick red to a bright orange-copper depending on how much dust, ash, and clouds are in Earth’s atmosphere on eclipse night. Major volcanic eruptions can darken eclipses for years afterward. Astronomers rate the brightness of a total lunar eclipse on the Danjon scale, from L0 (very dark, almost invisible) to L4 (bright copper-red).
The Stages of a Blood Moon
A total lunar eclipse runs through five stages over roughly 3 to 3.5 hours.
1. Penumbral eclipse begins. The Moon enters Earth’s lighter outer shadow. Subtle dimming. About an hour.
2. Partial eclipse begins. The Moon enters the deeper umbral shadow on one edge. Visible darkening, like a bite taken out. About an hour.
3. Totality. The whole Moon is inside Earth’s umbra. The Moon glows deep red. The classic blood-moon hour. Lasts roughly 60 minutes, depending on how centrally the Moon passes through the shadow.
4. Partial eclipse ends. The Moon exits the umbra, light returning from the opposite edge.
5. Penumbral eclipse ends. Full Moon visible again.
How Often Do They Happen?
Earth has 0 to 3 total lunar eclipses per year, sometimes none. Across any given location, a total lunar eclipse is visible roughly every 2 to 3 years on average. Unlike total solar eclipses, which require you to stand inside a narrow path of totality, a total lunar eclipse is visible from any location where the Moon is above the horizon during the event. Roughly half of Earth catches each one.
Recent and Upcoming Blood Moons
March 13 to 14, 2025. Total lunar eclipse visible across the Americas. Totality at 2:26 AM Eastern.
September 7 to 8, 2025. Total lunar eclipse visible across Europe, Africa, Asia, and Australia.
March 3, 2026. Total lunar eclipse visible across Asia and the western Pacific.
August 27 to 28, 2026. Partial lunar eclipse, not a blood moon, but worth watching.
Tetrads: Four in a Row
A “tetrad” is a sequence of four total lunar eclipses in a row, six lunar months apart, with no partial eclipses between them. They are uncommon. The most recent tetrad ran from April 2014 to September 2015. The next is projected for the early 2030s, around 2032 to 2033. Tetrads attracted intense religious-prophecy interest during 2014 to 2015. The astronomical pattern is real; the predictive claims attached to it have not held up.
Blood Moon, Supermoon, Harvest Moon: Different Things
The terms get mixed up.
Blood moon. A total lunar eclipse. Defined by Earth’s shadow.
Supermoon. A full moon that occurs when the Moon is at or near its closest approach to Earth (perigee). Defined by orbit, not light. Looks slightly larger and brighter than average.
Harvest moon. The full moon nearest the autumn equinox. Defined by calendar position, not appearance. Often looks orange because it rises low on the horizon, but no eclipse is involved.
A super blood moon is a real combination: a total lunar eclipse during a perigee full moon. They happen, though rarely.
How to Photograph a Blood Moon
The Moon during totality is much dimmer than a normal full moon. Settings to start: ISO 400 to 800, aperture f/5.6 to f/8, shutter 1 to 4 seconds. Use a tripod. Manual focus to infinity. White balance daylight. A telephoto lens of 200mm or longer is ideal for filling the frame. Bracket exposures because the brightness varies through totality.
For broader lunar context, see our pieces on the crescent moon and the far side of the moon.
Frequently Asked Questions
What is a blood moon?
A blood moon is a total lunar eclipse, when Earth’s shadow completely covers the Moon and the Moon glows deep red or copper. The color comes from Earth’s atmosphere refracting red wavelengths of sunlight onto the lunar surface.
Why does the Moon turn red during an eclipse?
Earth’s atmosphere bends sunlight inward into the shadow. Blue wavelengths scatter away; red wavelengths bend through and reach the Moon. The Moon is essentially being lit by every sunrise and sunset on Earth at once.
When is the next blood moon?
The next total lunar eclipse is March 3, 2026, visible across Asia and the western Pacific. The most recent total lunar eclipses were March 13 to 14, 2025 (Americas) and September 7 to 8, 2025 (Europe, Africa, Asia, Australia).
How long does a blood moon last?
Totality (the deep red phase) lasts about 1 hour. The full eclipse from start to finish, including the partial and penumbral phases, runs about 3 to 3.5 hours.
Does NASA call it a blood moon?
No. NASA officially uses “totally eclipsed Moon.” Blood moon is a popular name that predates space-era terminology. Both refer to the same event.
What is the difference between a blood moon and a supermoon?
A blood moon is a total lunar eclipse, defined by Earth’s shadow. A supermoon is a full moon at the Moon’s closest approach to Earth, defined by orbit. Different events. A super blood moon, when both happen at once, is rare but real.
- Josh Morley
