About Blood Moon:
- A blood moon is the dramatic red glow of the moon during a total lunar eclipse.
- Occurrence of Blood Moon
- A blood moon occurs when Earth comes directly between the Sun and the moon.
- A process called Rayleigh scattering causes the moon to appear red instead of dark.
- This happens because shorter-wavelength light (blue) is scattered, while longer-wavelength red light passes through the Earth’s atmosphere, making the moon appear red.
- During totality, “the entire Moon falls within the darkest part of Earth’s shadow, called the umbra.
- When the Moon is within the umbra, it appears red-orange.” This colour shift is what earns the event its nickname, the “blood moon.
- Depending on external factors such as atmospheric conditions and light pollution, the moon, during a blood moon phase, may appear red, orange, or copper-coloured.
What is Rayleigh scattering?
- It was explained by the British Nobel laureate John William Strutt (Lord Rayleigh) in the 19th century.
- When light interacts with particles smaller than its wavelength, the intensity of the scattered light is inversely proportional to its wavelength.
- This is the reason the earth sky appears blue: it has the shortest wavelength in visible light.
