[Reading Science] 'Aurora Festival' Unfolding in the Night Sky of Northern Europe

Recent Strong Solar Winds Blow
Auroras Observed Across UK and North America

Recently, strong solar activity has adorned the night skies over Northern Europe and North America with spectacular and beautiful auroras.

The space news outlet Space.com reported on the night of the 27th (local time) that the skies across the UK, including London, were covered with stunning auroras. Citizens in Scotland, North Wales, Ireland, and southern England have been uploading thousands of aurora photos on Twitter. Especially, the fantastic aurora photos taken at the ancient site of Stonehenge in Wiltshire, UK, resemble an alien planet from a sci-fi movie. Reports of aurora sightings have been received not only along the Atlantic coast, Canada, and Alaska but even in New York and Ohio in the United States.

Aurora decorating the night sky over Stonehenge, a representative ancient site in the UK, on the 27th (local time). Photo by Twitter

This widespread and intense aurora phenomenon is due to two simultaneous physical events occurring on the sun on the 24th. A phenomenon called a "coronal hole," where the flow of solar wind is emitted at a faster speed than usual, is pouring a strong magnetic field toward Earth. At the same time, a coronal mass ejection (CME), a powerful plasma explosion from a sunspot, also occurred. As a result, the speed and amount of solar particles pouring into Earth have greatly increased. When these particles collide with oxygen, nitrogen, and other elements in Earth's atmosphere, the aurora phenomenon, which burns brightly, has significantly intensified.

Aurora observed across the UK on the 27th (local time). Photo by Twitter

When the solar wind is weak, auroras can only be seen near the polar regions. However, currently, the solar wind is fast and strong, causing many particles to pour into Earth. This results in auroras occurring far from the North Pole, emitting powerful light. The color of the aurora varies depending on the type of particles colliding with the solar wind. Typically, oxygen emits green light, while nitrogen emits blue and purple hues. When the charged particles in the solar wind are particularly active, as they are these days, high-altitude oxygen can emit deep red light, and nitrogen can glow pink. This is why the aurora appears green in lower areas where oxygen is relatively abundant and red at higher altitudes.

Auroras observed on the night of the 27th (local time) in the UK, Canada, and Alaska. Photo by Twitter

Meanwhile, the US Space Weather Agency predicted on the 28th that a G3-class geomagnetic storm, capable of producing even more astonishing aurora observations than the previous day, would occur. They also warned that it could somewhat affect power grids and supply in high-latitude regions and cause transmission disruptions for satellite operators.

Aurora observed on the night of the 27th (local time) across the UK, Canada, and other parts of North America. Photo by Twitter

Aurora observed on the night of the 27th (local time) across the UK, Canada, and other parts of North America. Photo by Twitter

Aurora observed on the night of the 27th (local time) across the UK, Canada, and other parts of North America. Photo by Twitter

Aurora observed on the night of the 27th (local time) across the UK, Canada, and other parts of North America. Photo by Twitter