A Blood Moon is a colloquial term that refers to the reddish appearance of the Moon during a total lunar eclipse. However, the phrase also refers to other events that turn the Moon red.
What Is a Blood Moon?
People use the term blood moon to describe any instance when the Moon appears red, not just during a total lunar eclipse. This broader definition includes cases where the Moon takes on a reddish hue due to atmospheric conditions such as smoke, dust, or pollution. Here’s how these different red Moons occur:
- Total Lunar Eclipse (Classic Blood Moon) – During a total lunar eclipse, the Moon turns red because Earth’s atmosphere scatters shorter wavelengths of light while allowing longer red wavelengths to reach the Moon. This is the most common and scientifically recognized use of blood moon.
- Moon Appearing Red Due to Smoke or Pollution – Wildfire smoke, volcanic ash, or heavy pollution scatter sunlight in Earth’s atmosphere, giving the Moon a reddish or orange tint even when there is no eclipse. This often happens when the Moon is low on the horizon, as the light must pass through a thicker section of the atmosphere filled with particulates.
- Red Harvest Moon or Red Supermoon – When the full Moon rises just after sunset, it often appears reddish due to Rayleigh scattering—the same effect that makes sunsets red. This occurs because the Moon’s light is passing through more of Earth’s atmosphere near the horizon.
- Lunar Opposition Effect – In rare cases, atmospheric conditions and optical scattering make the Moon appear red even when high in the sky, although this is less common than when it is near the horizon.
Why the Total Lunar Eclipse Definition Is Most Common
Although the term blood moon technically applies to any red-colored Moon, it is most commonly associated with total lunar eclipses. This is because:
- A total lunar eclipse reliably produces a deep red color due to the physics of light scattering.
- Other red Moon occurrences are highly variable and dependent on local atmospheric conditions.
- The term blood moon has historical ties to eclipses, particularly in folklore and modern media.
However, it’s worth noting that the broader usage has gained traction in recent years, particularly in weather and astronomy discussions where people observe reddish Moons due to wildfires or pollution.
How a Total Lunar Eclipse Works (and Why a Blood Moon Is Red)
A total lunar eclipse transpires when Earth aligns directly between the Sun and the Moon. The Earth’s shadow falls upon the lunar surface. As the Moon moves into Earth’s umbra (the central, darkest part of its shadow), it gradually darkens before adopting a reddish hue. This effect is due to Rayleigh scattering, where Earth’s atmosphere filters out shorter blue wavelengths, allowing red and orange wavelengths to illuminate the Moon.
Not All Total Lunar Eclipses Are Red
It’s important to note that not all total lunar eclipses produce a vividly red Moon. Sometimes the Moon appears coppery, brown, or black (invisible). The intensity of the color depends on Earth’s atmospheric conditions at the time of the eclipse. Factors such as volcanic eruptions, wildfires, or significant pollution introduce particles into the atmosphere, affecting the scattering of light and, consequently, the shade of the eclipsed Moon.
The Danjon Scale
Astronomers utilize the Danjon Scale to classify the visual appearance and brightness of lunar eclipses:
- L=0: Very dark eclipse; Moon almost invisible.
- L=1: Dark gray or brownish eclipse; details distinguishable with difficulty.
- L=2: Deep red or rust-colored eclipse; dark central shadow with brighter edges.
- L=3: Brick-red eclipse; umbra shadow usually has a bright or yellow rim.
- L=4: Very bright copper-red or orange eclipse; umbra shadow has a bluish, very bright rim.
This scale helps observers describe and compare the visual characteristics of different lunar eclipses.
When Is the Next Blood Moon? Table of Total Lunar Eclipses
Here is a list of total lunar eclipses through 2050. Note that the color of the eclipse depends on the weather as well as the configuration of the eclipse, so whether the moon is a “blood moon” or not is unknown:
| Date | Time (UTC) | Visibility Regions |
|---|---|---|
| March 14, 2025 | 03:57 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| September 7, 2025 | 18:12 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| March 3, 2026 | 12:00 | East in Europe, Asia, Australia, North America, South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| December 31, 2028 | 19:52 | Europe, Asia, Australia, Africa, north/west North America, Pacific, Atlantic, Indian Ocean, Arctic |
| June 26, 2029 | 11:22 | Europe, west in Asia, Africa, North America, South America, Pacific, Atlantic, Indian Ocean, Antarctica |
| December 20, 2029 | 02:23 | Europe, Asia, north/west Australia, Africa, North America, South America, Pacific, Atlantic, Indian Ocean, Arctic |
| April 25, 2032 | 07:22 | South/east Europe, Asia, Australia, much of Africa, much of North America, Pacific, Atlantic, Indian Ocean, Antarctica |
| October 18, 2032 | 16:07 | Europe, Asia, Australia, Africa, much of North America, north/east South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| April 14, 2033 | 02:13 | Europe, Asia, Australia, Africa, much of South America, Pacific, Atlantic, Indian Ocean, Antarctica |
| October 8, 2033 | 07:23 | East in Europe, Asia, Australia, North America, South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| March 3, 2036 | 16:22 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| August 7, 2036 | 18:12 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| January 31, 2037 | 02:16 | Europe, west in Asia, Africa, North America, South America, Pacific, Atlantic, Indian Ocean, Antarctica |
| July 27, 2037 | 14:45 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| January 21, 2038 | 06:30 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| July 16, 2038 | 22:03 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| December 10, 2041 | 09:42 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| June 5, 2042 | 19:32 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| November 29, 2042 | 04:47 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| May 25, 2043 | 14:14 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| November 18, 2043 | 22:26 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| May 14, 2044 | 06:39 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| November 7, 2044 | 16:56 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| April 3, 2047 | 09:56 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| September 27, 2047 | 21:42 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| March 23, 2048 | 11:53 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| September 17, 2048 | 02:12 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| March 13, 2049 | 16:44 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| September 7, 2049 | 06:24 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica |
| February 1, 2052 | 10:12 | Europe, much of Asia, much of Australia, much of Africa, North America, South America, Pacific, Atlantic, Arctic, Antarctica |
| July 28, 2052 | 00:45 | Europe, Asia, Australia, Africa, west in North America, east in South America, Pacific, Atlantic, Indian Ocean, Arctic, |
How to Watch a Blood Moon Eclipse
While you can’t watch a total solar eclipse without eye protection, viewing a total lunar eclipse is perfectly safe. Observing a blood moon eclipse requires no special equipment, making it one of the most accessible celestial events. Here are some tips for viewing:
- Check the Date and Time – Find out when the eclipse will occur in your time zone. Some phases of the eclipse are not visible everywhere.
- Find a Clear Sky – Light pollution does not significantly affect lunar eclipses, but cloudy skies obstruct the view. Choose a location with an unobstructed view of the sky.
- Consider Your Comfort – You might need a chair, insect repellent, or a coat, depending on the season.
- Watch the Entire Event – A total lunar eclipse lasts for several hours, with different stages: penumbral, partial, totality, and then back to partial and penumbral.
- Use Binoculars or a Telescope – The reddish color is visible to the naked eye, but optical aids enhance the details of the Moon’s surface.
- Photograph the Eclipse – A camera with manual settings or a smartphone with a zoom lens captures stunning images of the blood moon.
FAQs About the Blood Moon
1. What causes a blood moon?
A blood moon occurs during a total lunar eclipse when Earth’s atmosphere scatters shorter wavelengths of light, so only red and orange hues illuminate the Moon.
2. Is every total lunar eclipse a blood moon?
No, some total lunar eclipses appear dark gray, brown, or even nearly black depending on atmospheric conditions such as volcanic ash, dust, and pollution levels.
3. Can a blood moon predict disasters?
No scientific evidence supports claims that blood moons predict disasters. This belief stems from ancient myths and modern interpretations, but lunar eclipses are natural and predictable events.
4. How long does a blood moon last?
The total eclipse phase, when the Moon is fully within Earth’s umbra, lasts anywhere from a few minutes to over an hour. The entire event spans several hours.
5. Why doesn’t the Moon disappear during a total lunar eclipse?
Although the Earth blocks direct sunlight, the atmosphere bends and filters sunlight. So, there is still some red, orange, and yellow light faintly illuminating the Moon.
6. What is the rarest lunar eclipse color?
A completely black or deep brown lunar eclipse (Danjon scale L=0 or L=1) is rare and usually caused by extensive atmospheric debris from volcanic eruptions or other large-scale events.
7. Does a blood moon affect human behavior?
There is no scientific basis for claims that blood moons impact human behavior, emotions, or events on Earth beyond their visual spectacle.
8. What is the difference between a blood moon and a supermoon?
A blood moon is a total lunar eclipse, while a supermoon occurs when the Moon is closest to Earth in its orbit, appearing slightly larger. A “super blood moon” happens when both events coincide.
9. Can a blood moon be seen from everywhere on Earth?
The blood moon is only visible in regions where the Moon is above the horizon during the eclipse. Some areas see the entire eclipse, while others only observe partial phases.
10. How often do blood moons occur?
Total lunar eclipses happen roughly every two to three years, though not all are equally visible worldwide.
References
- Deans, Paul; MacRobert, Alan M. (2006). “Observing and Photographing Lunar Eclipses”. Sky & Telescope. F+W.
- Hagee, John (2013). Four Blood Moons: Something Is About to Change. Brentwood, TN: Worthy Publishing. ISBN 9781617952142.
- Karttunen, Hannu (2007). Fundamental Astronomy. Springer. ISBN 9783540341444.
- Mucke, H.; Meeus, J. (1992). Canon of Lunar Eclipses -2002 to +2526 (3rd ed.). Astronomisches Büro Wien.
- NASA. Lunar Eclipse Essentials (video).