The film was last seen in 2003. At that time, the great “Halloween storm”, the strongest solar storm in modern times, hit Earth. As a result, orange auroras were seen across North America and northern Europe.
Now photographer Harlan Thomas has managed to take a similarly colorful photo. He achieved this on October 19 west of Calgary, Alberta, Canada. About three days ago, the Sun sent a massive, slow-moving coronal mass ejection (CME) toward Earth.
This solar storm produced seemingly bright, pumpkin-colored, almost dancing columns, as Thomas’s photo shows. The catch: There should be no orange northern lights.
“Orange is huge, unbelievable,” Thomas said Space weather Exciting. “The pillars in the middle glowed for over 20 minutes.” The problem: There is nothing in Earth’s atmosphere that can produce the bright orange color of the northern lights in Thomas’s photo.
Auroras occur when CMEs, or high-energy particles from the solar wind, pass through Earth’s magnetosphere, magnetosphere, and superheated gas molecules in the upper atmosphere. Molecules thus excited release energy in the form of light.
What color this light shows depends on which organ is stimulated. The two most common aurora colors, red and green, are both emitted by oxygen molecules, but at different altitudes. If solar particles penetrate deeper into the atmosphere, they may also trigger the rare pink northern lights. In doing so, they superheat the nitrogen molecules.
As Spaceweather reports, theoretically oxygen and nitrogen molecules can produce orange light under certain conditions. However, this orange will be masked by the other colors of the surrounding molecules. This means seeing the orange auroras is almost impossible.
Kelmer Oksavik, a space meteorologist and aurora expert at the University of Bergen in Norway, has an explanation. “This leads to a combination of the two processes [rote und grüne Polarlichter] Come on, it tricks the camera and the eye into thinking it’s orange,” said the expert. In fact, the northern lights are red and green at the same time, making them appear orange.
Accordingly, Thomas’ image would have captured only the rare combination of red and green lights. But in any case it’s awesome.
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