Aurorae over Donegal, Ireland - OPOD

Aurorae over Donegal, Ireland - OPOD

On the night of February 27th to 28th, 2014, an extraordinary celestial event took place over Ireland and the UK. A solar coronal mass ejection (CME) caused a rare and intense auroral display that extended far south, captivating observers with its magical beauty. Among those fortunate enough to witness this awe-inspiring phenomenon was Peter O'Toole, who captured the spectacle using ultra-wide 8 and 16mm fisheye lenses. In this article, we will delve into the captivating world of aurorae and explore the science behind these mesmerizing light shows.

Aurorae occur when low-energy solar protons and electrons, concentrated in streams such as those emitted during a CME, penetrate the Earth's magnetosphere through openings. The magnetosphere acts as a protective shield, but when the magnetic fields of the sun and Earth are in opposition, particles can leak through holes in this shield. These particles are then trapped within the long plasma sheath tail that surrounds our planet.

Within this magnetic bottle, known as Earth's magnetotail, magnetic reconnections and rearrangements occur. These processes eventually lead to the acceleration of some particles downwards towards the Earth's atmosphere, while others are ejected into space. The particles that descend collide with the upper atmosphere and excite oxygen atoms. Some of these atoms remain collision-free long enough to emit the characteristic red and green light of the aurora.

The vibrant colors of the aurora are a result of the specific wavelengths of light emitted by excited oxygen atoms. Oxygen molecules at different altitudes emit different colors, with lower altitudes producing green light and higher altitudes producing red light. These colors create a breathtaking display that dances across the night sky.

The intensity and extent of an auroral display depend on various factors, including the strength of the solar wind, the orientation of the interplanetary magnetic field, and the location of the observer. Geomagnetic storms, such as those caused by CMEs, can enhance the likelihood and intensity of aurorae, pushing them further south than usual.

Ireland and the UK are not typically considered prime locations for witnessing aurorae. However, during particularly strong solar events, like the one in 2014, these countries can experience rare and remarkable displays. The unique geography of Donegal, Ireland, situated on the north coast, provided Peter O'Toole with an ideal vantage point to capture the stunning beauty of the aurorae.

Aurorae have fascinated humans for centuries, inspiring myths and legends across different cultures. From the ancient Greeks associating them with the goddess Aurora to indigenous peoples believing they were spirits or ancestors dancing in the sky, these captivating light displays have sparked our imagination throughout history.

In conclusion, the occurrence of aurorae over Donegal, Ireland, in 2014 was a rare and extraordinary event. The interplay between the solar wind, Earth's magnetosphere, and atmospheric particles creates a mesmerizing display of colors that captivates observers. While typically more common in polar regions, under certain circumstances, such as intense solar activity, aurorae can be seen further south. The images captured by Peter O'Toole serve as a reminder of the astonishing beauty that can be found in our night sky.

Aurorae over Ireland

A solar coronal mass ejection produced a rare intense auroral display far south over Ireland and the UK on the night of 27/28 February 2014. Peter O'Toole saw the magical scene on the north coast of Donegal, Ireland. He captured it with ultra wide 8 and 16mm fisheye lenses.

All images ©Peter O'Toole, shown with permission

Right: Low energy solar protons and electrons when in concentrated enough streams (as from CMEs) and when the solar and Earth magnetic fields are opposed leak through holes in Earth's magnetosphere.

There they are stored in the magnetic bottle of Earth's long plasma sheath tail.

Magnetic reconnections and rearrangements eventually accelerate some downwards (others are ejected into space).

The now high energy particles collide with the upper atmosphere and excite oxygen atoms. Some of these remain collision free long enough to radiate the forbidden red and green light of the aurora.

See 100 hours in the life of a proton.

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