Northern Ireland night sky phenomenon 'beyond words,' says photographer
There was a stunning display of the Northern Lights over Northern Ireland on Sunday night and as well as a phenomenon called STEVE.
Two CMEs (Coronal Mass Ejections) hit the earth on Saturday and on Sunday. This made a class G3 geomagnetic storm, often associated with the appearance of the aurora.
The northern lights were usually observed across all parts of the UK. In In this case a lesser observed feature but perhaps more spectacular was observed - STEVE.
Local astro-photographer captures STEVE perfectly
Martin McKenna, an astro-photographer was in Swatragh on Sunday night with his friend Conor McDonald. He has been observing the aurora from Northern Ireland since 1998. Since then he has observed over 180 displays.
"We knew there was a high chance of something big happening. A CME had hit the previous night, then at 9am on Sunday a second CME hit, then over an hour later a third CME hit, this combination of events enhanced activity to striking levels which would peak at G3 on the geomagnetic scale.
"The Bz component of the magnetic field dipped to -30, which is a sign of very strong potential. It was just a question of waiting until darkness to see what would manifest."
Martin continued: "The aurora itself was so high it reached the north star 'Polaris' and beyond. The sight of these huge beams slowly slicing through the sky in their multitudes was beyond words.
"The highlight, however, was a rare phenomenon called STEVE which took the form of a long beam of light crossing the entire sky from west to east where it flared in brilliance near the planet Jupiter.
"We had never seen one in our lives in over 25 years of sky watching, and tonight it was clearly visible, it was this phenomenon which we didn't expect to see, what a treat it was!"
What is STEVE?
STEVE stands for Strong Thermal Emmisions Velocity Enhancement. This is an atmospheric optical phenomenon that appears like a ribbon in the sky. STEVE was spotted in the sky on Sunday night.
The atmospheric optical phenomenon is caused by a flowing ribbon of hot plasma breaking through into the earth's ionosphere, appearing in the sky as a purple, red and white arc.
What is the difference between STEVE and the aurora borealis?
Despite appearances, STEVE differs to the northern lights as it is formed of a thinner, single arc-shaped band, rather than the more "spread out" look of the aurora borealis.
According to the European Space Agency, a typical aurora is caused by energetic electrons traveling down Earth’s magnetic field.
When those electrons collide with the atmosphere roughly 100km above Earth’s surface, they excite atoms which then emit red, green, and violet light.
In contrast, STEVE does not appear to be caused by energetic electrons, and is white, purple and red in colour.
How rare is it to see STEVE?
First named by aurora watchers in Canada in 2016, it is relatively new to scientists, according to US space agency NASA.
However, the STEVE phenomenon is not rare and has been observed in photographs for decades but only recently investigated by scientists with the advancements of satellites.
The European Space Agency has a three-satellite 'Swarm mission' and this is dedicated to unravelling one of the most mysterious aspects of our planet: the magnetic field.
One of the satellites flew threw STEVE in 2017 and it measured a jump in temperature by 3000°C at 300km above the Earth’s surface. The data revealed a 25 km-wide ribbon of gas flowing westwards at about 6 km/s compared to a speed of about 10 m/s either side of the ribbon.
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