Moonrise in an Anti-Twilight Arch
The next time you see the sun setting, turn your back on it and look in the opposite direction for the anti-twilight arch, a band of colors ranging from reds to purples, created by light from the setting sun. Below the arch, you will see dark blue—the shadow of the earth cast on the atmosphere by the setting sun.
In the picture above, a full moon is rising in the anti-twilight arch. The winter months, when the sun sets earliest, are an excellent time to view an anti-twilight arch. Sadly enough, it also helps if there are pollutants in the air, which contribute to atmospheric scattering, making the colors of the arch more intense.
Photo by Paul Doherty
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