What is a blood moon?
A blood moon is a total lunar eclipse. When the Moon passes completely into Earth's shadow, it doesn't go dark: sunlight bent through Earth's atmosphere lights it a deep orange or red. It is completely safe to watch with your eyes.
Key facts
| What it is | A total lunar eclipse |
|---|---|
| Color | Copper, orange or deep red; varies each time |
| Safe to look at? | Yes, no glasses needed |
| Longest possible totality | About 1 hour 46 minutes |
| Next blood moon | December 31, 2028 |
Why the Moon turns red
During a total lunar eclipse, Earth sits directly between the Sun and the Moon. No direct sunlight reaches the Moon, but Earth's atmosphere acts like a lens: it bends a little sunlight around the planet and into the shadow. On the way, the air scatters away most of the blue light (the same effect that makes the sky blue), so what reaches the Moon is mostly red and orange. In effect, the Moon is lit by every sunrise and sunset on Earth at once.
Why every blood moon looks different
The exact color depends on what is in Earth's atmosphere. After large volcanic eruptions, extra dust and droplets high in the atmosphere can make the eclipsed Moon very dark, sometimes almost invisible. With clear air it can be bright copper. Astronomers grade the color on the Danjon scale, from 0 (very dark) to 4 (bright orange). How deep the Moon goes into the shadow matters too: the edge nearest the shadow's center is usually darker.
How to watch one
You need nothing but a clear sky and the Moon above your horizon. Binoculars or a small telescope show the color changes across the Moon's face beautifully. The whole eclipse, from the first bite to the end, can take more than three hours; the red total phase is the middle part. Use the eclipse calculator to see times for your own city, or moonrise and moonset to check the Moon is up.
Upcoming total lunar eclipses
- December 31, 2028
- June 26, 2029
- December 20, 2029
- April 25, 2032
- October 18, 2032
- April 14, 2033
- October 8, 2033
Not every one is visible everywhere: a lunar eclipse can be seen from anywhere the Moon is above the horizon at the time, which is roughly the night side of Earth.
Questions people ask
Is a blood moon dangerous?
No. It is a normal lunar eclipse and is completely safe to look at. The name is popular, not scientific.
How often is there a blood moon?
Total lunar eclipses happen about once or twice a year somewhere on Earth, but some years have none. Any given place sees one every few years.
What is the difference between a blood moon and a supermoon?
A blood moon is a total lunar eclipse. A supermoon is a full moon that happens near the Moon's closest point to Earth, so it looks slightly larger and brighter. They can happen at the same time.
Sources
Last updated October 20, 2026. Found an error? Tell us.