This article was originally published on 21 September, but is being published again as there has been a lot of aurora activity recently and there is a chance of another significant storm on Thursday night.
IT TOOK ME two decades to get over the disappointment of 2003, when one of the strongest geomagnetic storms of the modern era smashed into Earth.
Parts of the world where aurora borealis are not normally visible to the naked eye were treated to a show of vivid colours dancing in the night sky.
My dad and I had spent countless evenings staring at the northern horizon, but hadn’t succeeded in seeing the aurora. Unfortunately, on this occasion, we missed the memo.
Fast-forward to 10 May 2024. Another massive storm arrived, exceptional not only in its scale, but because it was a clear, cloudless, mild night in Ireland with the aurora active as soon as night fell. This allowed a huge number of people to witness it.
That included this journalist, who had trekked up to an isolated hillside in rural Wexford to finally, finally, see the northern lights.
Apologies in advance, I will be going on about this for months. pic.twitter.com/tmYhNnxSZR
— Nicky Ryan (@NickyRyan_) May 10, 2024
But like buses, you wait two decades for a chance to see the aurora and three come along at once: careful editing of a photo from March revealed the telltale glow. This month, another glow appeared in the sky over Ireland’s Eye.
Head over to Facebook, join an aurora chaser group or two, and you would start to wonder how I didn’t see it more often. You’ll find amateur stargazers proudly sharing images of the aurora they took with seemingly relative ease on numerous occasions this year — and from places like Cork, not Lapland.
The comments are filled with people who tried or failed to see it, maybe expecting an incredible light show when in reality, it usually takes a little bit more work to see it that way.
Others didn’t even know it was happening. Sometimes, everyone is in the same boat when the forecasted storm fails to materialise.
Aurora borealis at the Fairy Tree, Knockbridge, Louth late last night. pic.twitter.com/aXvlAIg6EC
— Sryan Bruen Photography (@sryanbruenphoto) September 13, 2024
So what’s happening? How is what was once considered a rare, almost mythical, event become more common? And if so, why is it still so hard to see and forecast?
The Journal spoke to Wil Cheung, an astronomer and fellow of the UK’s Royal Astronomical Society, who shares aurora photos and advice on his Facebook page Wil Photography.
“What we’re experiencing is the solar maximum,” Cheung explained, the peak of a roughly 11-year cycle in the Sun’s activity.
So right now, literally almost every month, we’re getting some kind of decent storm.
The science here can be sometimes tricky to wrap your head around, so we’ll keep it simple:
Put simply: the Sun burps; right now, its burps are louder than normal; sometimes these burps are a little spicy; if the burp is directed at Earth, we might hear it, but we won’t always smell it.
This energy can also cause damage to satellites and power grids (Canada experienced blackouts in 1989, Sweden and South Africa in 2003). Radio blackouts are common.
The 1859 Carrington Event resulted in an aurora display so bright that it woke people up and with so much energy that it set telegraph equipment on fire. An event of this magnitude happening today is cited as a potential doomsday scenario.
The Sun’s activity is just one part of the picture. Solar flares and CMEs occur at all stages of the solar cycle. During the solar minima, coronal holes are more commonly responsible for aurora and are easier to predict in advance.
A crucial element, Cheung said, is the modern smartphone.
“The problem is that most of the time, the aurora really is only visible by camera when it’s not super-super bright,” Cheung said.
Advanced image sensors in phones mean you can now take a reasonably clear long exposure photo, which lets in more light than a normal photo and makes dark scenes brighter. You might not even need a tripod.
For us in Ireland, this is crucial. In the likes of northern Scandinavia, aurora can be visible in colour with the naked eye. Here, that level of visibility is not unheard of (especially in very dark and/or northern parts of the island) but it is rare, with aurora more commonly appearing like grey wisps.
Faint aurora can still only be captured using professional equipment, but now people who previously might have thought they missed the lights are at least able to see it on camera.
Most people over the years have missed it; it’s actually been up there, but they just didn’t know.
In addition to as little cloud cover and light pollution as possible, a clear view north, and ideally no moonlight, you need to know if the aurora is actually happening at all.
But our ability to accurately forecast this is frequently overestimated.
Headlines might light up with news of an approaching CME, but sometimes the sky does not. Experienced aurora chasers, having been burnt many times before, treat these stories with reserve.
Cheung explained that when a CME erupts from the Sun, scientists try to determine its strength, speed and direction, but it’s an imperfect science.
The estimate of when it might hit Earth can be off by as much as 12 or more hours.
We know little until the cloud reaches satellites sitting in a fixed point between Earth and the Sun. This is one of the best ways to determine if CME will hit Earth and gives clues as to its chances of causing aurora:
Everything else [before that] should be taken with a pinch of salt.
Even then, we only get between a 15- and 60-minute warning that it will arrive. It might be weaker than expected, or other factors mean it might not result in aurora.
Then, once the CME is sweeping past Earth, its power, density, speed and orientation can ebb and flow, something which can be estimated a little further in advance than its arrival.
Conditions can quickly become more favourable for aurora and cause a ‘substorm’.
Aurora chasers watch this information carefully as night approaches, then use it to make the call whether to head to their chosen viewing spot. Once there, they might also rely on it to decide when to pack up their equipment and head home to warm up.
Access to the raw data has been greatly democratised. Glendale App, managed from the township of the same name on the Isle of Skye by Andy Stables, is just one popular hub for this. Information from a whole range of sources is combined into one interface.
It’s dense and complex, but Stables has worked to make it less intimidating to newbies with helpful guidance and messages.
“The app itself is designed as an educational tool to highlight which things are important and make it easy to understand the substorm process and follow it in real-time,” he told The Journal in an email.
“Estimated times of arrival for CMEs should never be used by aurora hunters. Instead, you wait for the shock, when the CME hits the satellites between Earth and Sun, and check that the interplanetary magnetic field (IMF) is the right way up. Then, we know it is game on.”
The IMF mentioned is a crucial element, both in terms of its strength (measured in nT) and its orientation (known as Bz)… we’ll stop there. You can see how quickly we might get into the weeds.
Because of this, each section on the app has an interpretation of the data to explain what it means. There are info buttons to explain each metric so you can figure them out for yourself.
Stables also operates a Telegram bot, which sends out automated updates in real-time as the auroral substorm is happening and developing, with different alert levels. This is UK focused but when it comes to space weather rather than terrestrial weather, it is applicable to Ireland.
From his Facebook page, Cheung takes a slightly but complementary different tack, running an increasingly popular broadcast channel where he posts plain-language interpretations of the data and highlights when there’s a chance of seeing it by eye.
Cheung is hugely passionate about getting more people interested in aurora, and better educated in terms of how to see it for themselves (and, perhaps, temper expectations):
The one thing that I’m trying to educate people on is if you see it as a glow, it’s great, but you really want to see it at its best.
“There will be opportunities for us in [Ireland, the UK, and other mid-latitude regions] to see similar stories to 10 May over the coming months or years.
The main thing is notice. If we can help people to see it — ‘it is likely going to happen tonight’ or ‘we know what minute it is going to happen’ — we’ll have done our job.
“The data is there. It’s not magic.”
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