Northern Green Flash

Astronomy Picture of the Day · 2012-06-23 · NASA (public domain)

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Northern Green Flash — APOD for 2012-06-23

As seen from Frösön island in northern Sweden the Sun did set a day after the summer solstice . From that location below the arctic circle it settled slowly behind the northern horizon. During the sunset's final minute, this remarkable sequence of 7 images follows the distorted edge of the solar disk as it just disappears against a distant tree line, capturing both a green and blue flash . Not a myth even in a land of runes , the colorful but elusive glints are caused by atmospheric refraction enhanced by long, low, sight lines and strong atmospheric temperature gradients.

Astronomy Picture of the Day for 2012-06-23 — image & explanation courtesy of NASA (public domain), mirrored at Tukuk-OS for reading and search convenience.

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