BOISE, Idaho — On Sunday night, the sun, moon and Earth aligned, casting a shadow on the full moon’s surface, giving the moon a striking reddish hue; one reason why lunar eclipses are also known as blood moons.
This month’s full moon was a “super moon,” meaning it looks bigger and brighter than usual because of the close proximity to Earth in its orbit. The “flower” part comes from the May full moon’s spring-themed nickname.
The moon looks red during a lunar eclipse because of Rayleigh scattering, the same reason the sky is blue, according to NASA. Because of the longer wavelength, red light travels more directly through the atmosphere than blue light. The sun produces both wavelengths, but blue light is only visible from Earth’s surface when the sun is overhead.
During a lunar eclipse, blue light scatters in Earth’s atmosphere and only red light reaches the moon. It looks even redder if Earth’s atmosphere has a lot of light-blocking dust and clouds.
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