A group of scientists studied a mysterious aurora recorded in May 2024 in Japan. It had a blue color and reached unusually high heights. Apparently, this event indicates the presence of a natural process still unknown to science. What is the origin of the strange blue aurora?
In May 2024, a powerful geomagnetic storm caused a strange blue glow to appear at low latitudes. Physicists Sota Nanjo and Kazuo Shiokawa of Nagoya University propose an explanation. The research suggests that the molecular nitrogen ions may have been accelerated upward by some mechanism. This is how the blue aurora was formed. But how can such heavy ions exist at such high altitudes if they have short lifetimes?
Why does it happen?
«It is not easy for such ions to exist for long periods of time. It is because of its mass and the short time intervals of dissociative recombination. But they are observed at high altitudes. The process is surrounded by mystery,” say the researchers.
Typically, auroras are caused by a stream of solar particles ejected from the Sun during coronal ejections or solar winds. These particles collide with the Earth’s magnetic field and travel towards the poles. They interact with atmospheric gases, causing a glow.
Under normal conditions, they are red in color. But on May 11, 2024, the sky lit up with a pink glow, followed by a clear blue glow. It reached heights of between 400 and 900 kilometers, above the orbit of the International Space Station.
Frequent events
Low-latitude auroras are believed to be associated with charged particles within the Earth’s magnetosphere. But the ring current cannot fully explain the observed phenomenon. The molecular nitrogen ions have somehow been accelerated upward. It is not known how.
This suggests the possibility of an as yet unidentified process in Earth’s atmosphere. Researchers hope to take advantage of increased solar activity in the coming years. Repeated analyzes of these blue auroras may explain their formation. «The origin of the strange blue aurora is not known. But in the coming years, we expect to repeat this analysis much more frequently,” the researchers write. The study was published in Earth, Planets and Space.
