Enigmatic Blue Aurora Suggests Unexplored Atmospheric Phenomena

Picture an aurora, and you likely imagine green swirls dancing across a frozen sky. While green is common, auroras can display a variety of colors depending on altitude, location, and the atmospheric gases involved.

During a powerful geomagnetic storm in May 2024, an unusual blue aurora appeared at low latitudes, reaching extraordinary heights. Using images captured by citizen scientists in Japan, physicists Sota Nanjo and Kazuo Shiokawa analyzed the phenomenon. They suggest nitrogen molecular ions, accelerated upward by an unknown mechanism, created the eerie blue glow.

This raises a mystery: nitrogen ions are heavy and typically short-lived at high altitudes. How they persisted long enough to produce the aurora is unclear.

Auroras generally form when solar particles, expelled by the Sun in events like coronal mass ejections, collide with Earth’s magnetic field. These particles are funneled along magnetic field lines to the poles, where they energize atmospheric gases. As these gases return to their normal state, they emit photons, creating the aurora’s glow.

Aurora Colors and the Unusual Blue Glow of May 2024

Colors vary by gas and altitude. Oxygen produces green and red glows, while nitrogen emits blue and red. Unusually, the May 2024 storm caused pink and blue auroras at low latitudes. The researchers measured the blue aurora, noting it stretched 1,200 kilometers (750 miles) and reached altitudes of 400–900 kilometers, higher than the International Space Station’s orbit.

Low-latitude auroras are typically linked to Earth’s ring current, a torus of charged particles circling the equator. However, this phenomenon’s alignment with magnetic field lines suggests another mechanism was involved. The researchers hypothesize molecular nitrogen ions were accelerated upward, but what caused this remains unknown.

This enigmatic process hints at an undiscovered atmospheric mechanism. As solar activity increases in the coming years, more observations of such auroras may reveal the answers.

Read Original Article: Science Alert

Read More: Scitke