A recent solar storm slammed into Earth, creating what looks like bright pumpkin-coloured pillars dancing in the night sky over Canada, stunning new photography shows. But there’s a problem with the image: orange aurorae shouldn’t be there. Experts say that instead of impossible auroras, the image captures a rare combination of red and green light not seen since the terrifying Halloween solar storm that slammed into Earth 20 years ago.

“The orange was gorgeous, just incredible,” Aurora photographer Harlan Thomas said. “The pillars in the center continued to glow for more than 20 minutes.” Thomas captured this color image over a pond west of Calgary, Alberta, on October 19, about three days after the sun launched a powerful, slow-moving coronal mass ejection (CME) toward Earth.

Auroras are created when high-energy particles from CMEs, or the solar wind, bypass Earth’s magnetic shield, or magnetosphere, and superheat gas molecules in the upper atmosphere. Excited molecules release energy in the form of light, and the color of this light depends on which element is excited. The two most common aurora colors are red and green, both of which are emitted by oxygen molecules at different altitudes (red auroras are produced at higher altitudes than their green counterparts). But when solar particles penetrate deep into the atmosphere, they can also cause rare pink auroras when they excite nitrogen molecules.

Theoretically, both oxygen molecules and nitrogen molecules can emit orange waves under certain conditions. But even if this were to happen, orange would be overwhelmed by other colors emitted by the molecules surrounding it, making it nearly impossible to see those wavelengths, according to Spaceweather.com.

So how do we see this color in the last image?

“There may be a mixture of two processes [червоного та зеленого полярних сяйв]”This will trick the camera and the eye into thinking it’s orange,” said Kjellmar Oksavik, a space weather scientist and aurora expert at the University of Bergen in Norway. Spaceweather.com. “It’s actually red and green at the same time.”

Although red and green auroras are often seen together in the sky, “orange” auroras are very rare. Oksavik said the orange color is most visible at the center of large aurorae, which are vertical columns of light lined up along invisible magnetic field lines that are very rare and consist of both red and green light.

According to Spaceweather.com, such bright pumpkin hues were last seen during the Great Halloween Storm of 2003; This was the most powerful solar storm in history. Orange lights were seen across North America and Northern Europe during this epic event. Source