Lunar and solar halos are caused when light passes through ice crystals formed in clouds through the sky.
Credit: Shingo Takei
On a perfectly still winter night, the famous constellation Orion shone around a beautiful lunar halo in a photograph taken by a Japanese amateur astronomer.
The image shows the stars of Orion, the mighty hunter in the top right, along with the constellations Taurus (the bull) above it and Canis Major (the big dog) below it. The three constellations surround the glowing lunar halo in a stunning photo taken by astrophotographer Shingo Takei from Japan's Nagano prefecture.
Lunar and solar halos are caused when light passes through ice crystals formed in clouds in Earth's atmosphere. Ice crystals in a high, thin layer of cirrus clouds bend the light at a specific angle like a lens. Since each crystal has a similar hexagonal shape, light that enters typically refracts 22 degrees, creating the round halo shape. Such halos are fairly common in the night sky.
A beautiful but less common type of halo can occur when light is bent at 46 degrees. While the process is similar, it occurs when light enters one side of the crystal and exits from either the top or bottom of the crystal. The light is refracted twice, creating a larger halo around the sun or moon.
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