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If you're wondering what exactly happened last night, and why the Northern Lights were so clearly visible across our skies, then Dr Jean Dean from La Société Guernesiaise has the answers.
The Secretary for the Astronomy Section has explained why the high solar activity overnight created the light display so many people saw:
Pictured: Auroral activity Guernsey 10/05-24 image credit Jean Dean.
Auroras are the visible manifestation of a solar storm, associated with a coronal mass ejection, when high energy solar particles are discharged into space and head towards Earth where they can travel down the magnetic field lines at the north and south poles into Earth’s atmosphere.
The high energy particles transfer their energy to the oxygen and nitrogen atoms, making them “excited”. As the gases return to their normal state, they emit small bursts of energy in the form of light.
This process goes on all the time, but during high solar activity a large number of solar particles bombard the atmosphere, when the oxygen and nitrogen can emit enough light that it is detectable by the naked eye.
Pictured: Cartoon showing the aurora image credit NASA - supplied by La Societe Guernesiaise.
The colour of the aurora depends on which gas is being excited by the solar particles, and how excited it becomes. It also depends on how fast the solar particles are moving, the faster they are, the higher the energy at the time of collision.
High energy electrons cause oxygen to emit green light, while low energy electrons result in red light. Nitrogen tends to give off blue light. All these colours can be blended in a display to give shades of purples, pinks and whites.
Aside from being beautiful and mesmerising, the aurora show eloquently how the Earth’s magnetic field protects life on Earth.
Our neighbour Mars once had a magnetic field that protected the planet, and it had oceans and an atmosphere very similar to that of Earth. However, Mars lost its magnetic field as the intense bombardment by solar particles slowly stripped away its atmosphere and oceans, leaving behind an inhospitable, cold and dusty planet.
Descriptions of the aurora can be found in many early cultures, where ancients thought of them as great dragons or serpents in the skies. In Scandinavia, Iceland and Greenland where aurora is common, it was seen as the great bridge Bifrost, the burning archway between by which the gods travelled from Heaven to Earth.
Pictured: Jean Dean Secretary of the Astronomy Section La Société Guernesiaise.
At the moment solar activity is reaching a high as the latest 11-year cycle peaks.
Hopefully, there will be more opportunity this year to see the aurora. For the best viewing find a dark location and look towards the north. Ideally, let your eyes adjust to the dark and you will start to see more detail.
To keep informed on auroral activity and receive alerts to your phone see this website: https://aurorawatch.lancs.ac.uk
Dr Jean Dean
Secretary Astronomy Section of La Société Guernesiaise
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