A touch of pink in the sky Auroras are often seen with an impressive green color, but sometimes they
A touch of pink in the skyAuroras are often seen with an impressive green color, but sometimes they can show off other colors, such as red, blue or purple. However, pink auroras, as seen in the picture below, are a rare treat.Our sun is an active star, with solar flares erupting from the surface quite regularly. The eruptions send solar particles streaking through space and when these particles interact with gases in the Earth’s atmosphere, they produce a dazzling display of colored lights. The color of the light produced –which spans the visible spectrum (i.e.red-orange-yellow-green-blue-indigo-purple) – depends on what type of gas the particles interact with and also in what part of the atmosphere the reaction is taking place. Incoming particles are prone to collide with specific gases at different heights. For example, above 300km in the atmosphere, where oxygen is the most common gas, collisions generate a red light. Between 100-300km, collisions with oxygen produce yellow/green auroras, and around 100km, these collisions cause red light. Nitrogen molecules can glow red or blue, while hydrogen and helium produce colors such as blue or purple.As you can see, several colors can be radiated by distinct particles, but pink isn’t on the list, since it’s not a spectral color. In order to get pink, a source of collisions is required to create red and blue light and together these colors combine to appear pink or magenta. This means that when we see a pink aurora, what we actually see is the combination of red and blue light emitted by molecules from the upper atmosphere; our eyes just perceive this balance of the two colors as pink.There is no doubt that the auroras are one of nature’s most stunning shows, but if you ever get the chance to observe a pink aurora, you are quite the lucky person, since this is a rare phenomenon.– SuSources:http://bit.ly/2rkxjo8http://bit.ly/2rUpOD3Photo credit:http://bit.ly/2rc1ZUh - photo by Jan Curtis/Geophysical Institute at the University of Alaska, ACRC -- source link
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