National Current Affairs
Blood Moon
- 08 Sep 2025
- 3 min read
Why in News?
On 8th September 2025, skywatchers across Asia, Australia, and parts of Africa witnessed a spectacular Blood Moon—a total lunar eclipse where Earth’s shadow turned the Moon deep red.
- It was the year’s second total lunar eclipse after March 2025, lasting over five hours with 82 minutes of totality, and building anticipation for the August 2026 solar eclipse.
- Unlike a solar eclipse, lunar eclipses are safe to view with the naked eye.
Key Points
- Lunar Eclipse: A lunar eclipse occurs when the Sun, Earth, and Moon align in a straight line, with Earth positioned in the middle. This blocks sunlight from directly reaching the Moon.
- Total Lunar Eclipse: When the Moon passes through the Earth’s inner, darkest shadow (umbra), it appears deeply shaded or red.
- Partial Eclipse: When only part of the Moon passes through the umbra.
- Penumbral Eclipse: When the Moon enters only the outer shadow (penumbra), the dimming is subtle and often hard to notice.
- “Blood Moon” Effect: The “Blood Moon” effect happens because Earth’s atmosphere filters sunlight before it reaches the Moon. When light passes through our atmosphere:
- Blue light scatters easily (this is why our sky looks blue).
- Red light bends around Earth and reaches the Moon, causing it to glow red or coppery during a total eclipse.
- A bright red Moon suggests clearer air with fewer pollutants.
- A deeper red Moon signals more dust, ash, or pollution in the air, reflecting the condition of Earth’s atmosphere.
- Correlation: The phenomenon behind the Blood Moon is the same process that colours the sky and sunsets: Rayleigh scattering, first explained by physicist John William Strutt, 3rd Baron Rayleigh.
- Daytime Sky: Short-wavelength blue light scatters in all directions, making the sky appear blue.
- Sunrise & Sunset: Sunlight passes through thicker layers of atmosphere, scattering away blue light. What remains are long wavelengths — red, orange, and yellow.
- During a lunar eclipse, the Moon is essentially bathed in all the world’s sunsets at once, projected through Earth’s atmosphere.
