Shottess wrote:

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Ring Around the Sun

Solar halo - a ring around the Sun.

Have you ever looked up and noticed that there's a big ring around the Sun? These rings are caused by ice crystals within thin cirrus clouds, and there several different kinds of sun rings you can see depending on the weather conditions.

One of the most common ones is called a 22° halo. They get this name because the ring is located 22 degrees away from the Sun itself. Both the Sun and the Moon block a 1/2 degree region of the sky at a time, so the ring around the Sun is about 44 times larger than the Sun itself.

Why do you get a ring at exactly 22°? The ring is formed because of the ice crystals suspended in the cirrus clouds. If you could look at the crystals under the microscope, you would see that they're hexagonal in shape, and act as prisms for the Suns light. As light passes through the two sides of the prism, its deviated by exactly 22°. Since the ice crystals are jumbled up randomly in the sky, most of the light is deflected away. But from every position you're always able to see the deflected light from some of the crystals in the sky. And this is why you see the bright ring around the Sun.

When you're looking for halos, or rings around the Sun, make sure you always shield both eyes from the Sun. Even looking at the Sun for an instant can cause permanent eye damage.

-- Edited by Shottess on Saturday 6th of June 2009 08:43:06 PM

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