Scientists finally solve the mystery behind the first-ever 'polar rain' auroras on Earth

Mother Nature has blessed us with some incredible spectacles around the world and the Northern Lights are significant ones among them. The dancing aurora lights found in the Arctic region attract many spectators from around the world. But during Christmas 2022, a rare form of aurora was observed in the Arctic Sky for the first time ever and scientists were puzzled by its unusual characteristics. After much brainstorming, a team of Japanese and American scientists recently solved the mystery behind this oddly unwavering green glow. Their findings published in the Science Advances journal are an eye-opener about this new natural phenomenon.

In general, the spectacular event of Aurora is a result of a rather spooky occurrence. The dancing lights are created when energized particles from the Sun collide with Earth's upper atmosphere at high speed, as per Space.com. When our Earth's magnetic field redirects these particles toward the poles to protect us from these fast-moving particles, it turns into a visibly-pleasing atmospheric phenomenon. While it's called aurora borealis or Northern Lights in the North Pole region, it's termed aurora australis or Southern Lights in the South Pole. What was distinctive about the December 2022's aurora was that it lacked its usual auroral motions.

The All-Sky cameras (ASCs) located at the polar cap latitudes in Longyearbyen, Svalbard Island, Norway observed a steady, featureless green glow of aurora. Unlike its usual characteristic of bright dancing hues of varied shapes constantly moving across the sky, this aurora was particularly unwavering. Also, it was a uniform blanket with no variations in the hues and it spanned 2,485 miles (4,000 kilometers) in the Arctic Sky. This first-of-its-kind phenomenon kindled the interests of the scientists who compared this aurora with the image they captured with the Special Sensor Ultraviolet Scanning Imager (SSUSI) on the polar-orbiting satellites of the Defense Meteorological Satellite Program (DMSP).

Turns out, it was a rare type of aurora called the "polar rain" aurora. This happened because the high-energy electrons flowing out of a Sun's coronal hole weren't scattered and there was no solar wind from the Sun. It was a total coincidence that both the opening of the Sun's coronal hole and the absence of solar wind occurred at the same time. So, the usual fast-moving aurorae caused by the solar wind were replaced by a steady rain of "suprathermal," electrons over the North Pole. This polar rain formed a stationary, uniformly bright canopy of green over the Arctic region. "This incredibly smooth and gigantic form is distinctively different from a typical polar cap aurora. Thus, it cannot be categorized as any previously identified class of aurorae visible at polar cap latitudes," the study says.  

Speaking of the aurora, scientists, in 2023, claimed that the spectacular natural phenomenon will be intense in the next 18 months. Experts from The Solar Cycle 25 Prediction Panel predicted that the aurora activity will not only be more intense but will also be visible in more places, according to NBC News. Mark Miesch, a researcher at the University of Colorado, said, "Skywatchers are excited." They added, "When there’s a big disturbance in the magnetic field, then you’re more likely to see aurora at lower latitudes."