A recent coronal mass ejection event may trigger a stunning auroral display.
A giant solar flare released by an exploding reverse polarity or ‘backwards’ sunspot is likely to trigger breathtaking auroras in the Northern Hemisphere tonight.
The sunspot, AR3296, exploded at 11pm on 7 May, creating a coronal mass ejection that sent highly energetic particles hurtling towards the Earth at speeds exceeding 1,000 km/s. The event is similar, though not quite on the same scale, as the geomagnetic storm that hit Earth in late April, which caused the northern lights to be visible across the UK and US.
When these particles slam into the atoms and molecules in the Earth’s atmosphere, they exchange energy, resulting in the atmosphere being put into an excited state. It is this exchange of energy that creates the characteristic ghostly green waves of the aurora.
How to see the northern lights tonight
The northern lights may be visible tonight, 11 May, across the UK and US. However, the aurora is not guaranteed in all locations.
According to the Met Office, there is a chance of ‘moderate to strong geomagnetic storms’ tonight, with the aurora possibly visible as south as southern England this week. Predictions made by the Space Weather Prediction Center in the US suggest that midnight tonight may hold the best chance of viewing the aurora for those of us in the UK.
“No one knows for certain when and where the aurora will be seen – it’s one of the joys of aurora hunting. Just as a bird watcher may spend days, weeks, months or even years searching for a sighting of a rare creature, aurora hunting takes time and patience,” says Dr Alan Wood, a lecturer in space weather and space systems engineering at the University of Birmingham.
Using equipment based in Lancaster and northern Scotland, the Aurora Watch Project website displays when geomagnetic activity is above average, which increases your chances of seeing the northern lights.
Wood says: “If you’re looking for the aurora, you’ll need a clear night (the aurora is higher than any clouds). Go out of town, away from any bright sources of light. Give your eyes time (maybe 10 minutes) to adjust to the darkness. Start by looking north – this is where the aurora is most likely to be seen, but don’t forget to look straight up too.
“People naturally scan the horizon and sometimes miss beautiful sights by not looking above their heads. The aurora has fascinated people for centuries and, whether you see a spectacular display or just a green glow in the sky, it is always a sight to behold. Happy hunting!”
What is a sunspot?
“Sunspots are regions where the Sun’s magnetic field is particularly intense. They appear dark because they are cooler than the surrounding regions of the Sun. They are not cold though – they are still around 3,500oC – it’s just that they are cooler than the surroundings,” says Wood.
“The surface of the Sun rotates at different rates in different places and, as a result, the Sun’s magnetic field becomes twisted. When it becomes more twisted, we see more sunspots and we are more likely to get space weather events. One of the most beautiful of all space weather effects is the aurora, also known as the northern (or southern) lights.”
Reverse polarity sunspots are relatively rare, making up just 3 per cent of those observed, and have a magnetic field that is ‘backwards’ in comparison to other sunspots found in the same hemisphere of the Sun.
About our expert, Dr Alan Wood
Alan is a Lecturer in Space Weather and Space Systems Engineering ad is part of the Space Environment and Radio Engineering (SERENE) group in the School of Engineering. His work has been published in journals including Advances in Space Research, Space Science Reviews and Geophysical Research Letters.
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